Outreach services with a health specialism for people rough sleeping in the UK: An intervention optimisation study

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Outreach with a health specialism is an intervention aiming to remove barriers to healthcare by having health professionals deliver services directly to people in their own environment. Despite widespread use, currently there is limited evaluation evidence for the intervention in the UK. This study describes the intervention’s programme theory and reports the optimisation of components, implementation strategy and context to maximise intervention functioning across the UK health and housing system. It will be followed by a pilot cluster Randomised Controlled Trial with nested process and economic evaluation. Methods We conducted a mixed-method optimisation study in England between June 2024 and January 2025. The optimisation process comprised three research phases: development of candidate programme theory; refinement of programme theory; and confirmation of final programme theory and development of operational delivery plan. Research methods employed across optimisation phases were: rapid evidence review of intervention manual, training materials and evidence-base; three professional (n = 12 individuals) and lived experience (n = 7 individuals) stakeholder workshops; and semi-structured interviews with system stakeholder with experience of the intervention (n = 8). The final optimised intervention was reported according to the Template for Intervention Description and Replication (TIDieR) checklist. Results The programme theory describes intervention mechanisms, components, outcomes and context. We identified potential system inhibitors to intervention functioning in the UK, which include local variations in population profile, limited organisational capacity and availability of follow-on services. Recommendations for intervention optimisation were: integrating lived experienced voices into training; ensuring training aligns with person-centred, responsive, and trauma-informed principles; tailoring outreach; developing supervision and a peer-led community of practice; improving data generation and flow; nurses to attend appointments with clients; and empowering nurses to work with other sectors. Conclusion This is one of the first studies to generate a comprehensive programme theory for outreach with a health specialism and describe how it can be optimally delivered in the UK. A clear theoretical understanding of how and why the should work will support future outcome evaluation and potential scale-up. It also provides a useful methodological example of intervention optimisation. Trial registration: ISRCTN Registry ISRCTN11572394 (Registration 13/12/2024) homelessness outreach nurses intervention evaluation development optimisation Figures Figure 1 BACKGROUND People experiencing homelessness report poorer health outcomes than those who are housed ( 1 , 2 ), and have a risk of all-cause mortality that is around twice that found in the general population ( 3 ). This excess mortality is in part explained by higher exposure to alcohol, smoking, drug use, and mental disorders ( 4 ). Engagement with appropriate healthcare can be challenging due to perceived and enacted stigma from health professionals, a lack of timely provision, and complex administrative processes ( 5 – 7 ). Precarity in meeting physiological needs, such as housing, food and clothing, can mean that health is not prioritised ( 6 , 8 ). The evidence-base for interventions that promote healthcare engagement is mixed, with a lack of approaches that effectively remove barriers to service uptake, including access to appropriate accommodation ( 9 ). However, syntheses conducted by the National Institute for Health and Social Care Excellence (NICE) have identified the potential of integrated outreach services ( 10 , 11 ). As a result, associated guidelines recommend the use of multi-disciplinary teams to deliver mobile outreach provision to individuals who may not otherwise have access to, or engage with, existing health and social care provision ( 12 ). In 2023, the Centre for Homelessness Impact (CHI), commissioned by the UK Government’s Ministry of Housing, Communities and Local Government (the Department for Levelling Up, Housing and Communities at the time of funding), launched a programme of research to generate an evidence-base for service delivery. As part of this programme, it funded an evaluation of a specific model of outreach service for people experiencing homelessness, namely outreach with a health specialism. For the purpose of the study, outreach nurses were newly commissioned to deliver the health specialism, with Change Grow Live (CGL) ( https://www.changegrowlive.org/ ) serving at the intervention provider. Outreach with a Health Specialism Outreach with a health specialism aims to remove barriers to healthcare engagement by having health professionals deliver services directly to people in their own environment. For those who experience rough sleeping, this may be in a variety of locations, including on the street. The model is in routine practice across some areas of the UK, though reach can be variable and provision is often tailored to meet the needs of the local context. For the purpose of the current study, the intervention is based on a version of the model that has been delivered in central London ( 13 – 15 ). Despite best practice methodological guidance recommending that interventions have a clearly articulated programme theory describing the underpinning causal mechanisms ( 16 ), the theoretical basis of this approach is generally underspecified. Components tend to be more explicitly described, with the intervention delivering a wide range of potential activities. These include, but are not limited to, professionals providing health checks, offering health advice and screening, and offering vaccinations and some urgently necessary medications. Delivery agents commonly include nurses, dentists, General Practitioners (GPs) and pharmacists ( 8 ). While evaluations have been characterised by a lack of randomised study designs, there is some indication that outreach with a health specialism can increase uptake in vaccinations, screening and dental treatment, along with a reduction in emergency hospital visits and admissions ( 8 , 17 ). However, without a clear understanding of the mechanisms through which this type of intervention brings about change, the range of outcomes that can be plausibly targeted is not fully evident. This includes whether health outreach can improve access to appropriate accommodation and housing stability. Intervention Modelling and Optimisation In the current study we present the conceptual modelling of the outreach with a health specialism intervention evaluated as part of the CHI commission. We developed a programme theory describing: the components to be delivered; the implementation processes that ensures delivery; the causal mechanisms that components should potentiate; and the outcomes that should be impacted. Important to any generation of programme theory is an understanding of the intervention’s delivery context, and how features of the system will interact with causal mechanisms, working to support or inhibit the pathway to targeted outcomes ( 16 ). To date there is only a small body of qualitative evidence from the UK exploring how the health, social care and housing system might influence the functioning of health outreach ( 18 , 19 ). The vast majority of research has been conducted in the USA and Australia ( 10 ). There is limited systematic consideration of whether reported context-intervention are also characteristic of the UK. As such, there is a need to describe how the intervention might operate in the UK and explore any system specificities. Through the process of describing the programme theory, there is a possibility of identifying limitations with the intervention. This includes incompatibility between components, weaknesses in proposed causal pathways, contextual characteristics that will inhibit delivery, or outcomes that are not theoretically justified. In response, it may be necessary to optimise intervention components, implementation processes, and delivery context. Optimisation is a concept used across evaluation research and implementation science, broadly describing a data-driven process for improving interventions ( 20 ). It is increasingly recognised as a much needed phase of evaluation in homelessness research ( 21 ). In accordance with Medical Research Council guidance on the development and evaluation of interventions ( 16 ), we conceive optimisation as the process of refinement. It is done with the intention of enhancing intervention functioning, ensuring it is optimally designed to be feasible, acceptable and activate intended causal mechanisms. We differentiate this approach from optimisation evaluation research designs, as prescribed by the MOST guidance ( 20 , 22 ). These generally entail the randomised experiments of components to identify which ones best meet the optimisation criteria (e.g. most cost-effective). To note, our approach does have some alignment with the initial preparation phase of MOST, which takes a mixed method approach to identifying and piloting theoretically and empirically justified intervention components ( 23 ). However, where MOST progresses to a fractional-factorial Randomised Controlled Trial to compare intervention components, our optimisation process will be followed by a pilot cluster Randomised Controlled Trial. Research Questions In this paper we describe the process of developing the programme theory and optimising the intervention. Specifically, we address the following research questions: What are the intervention’s mechanisms, components and implementation processes, outcomes and relevant aspects of context? How can intervention components, implementation processes and context be optimised to enhance intervention functioning? How can the optimised intervention be operationally delivered? METHODOLOGY Design The optimisation phase comprised three stages of research: 1) rapid evidence review of intervention manual and training materials from the London model ( 13 – 15 ), along with the research evidence-base, to construct a candidate programme theory; 2) stakeholder and lived experience workshops and interviews to consider the accuracy of the candidate programme theory, address gaps in understanding, and identify necessary refinements to optimise intervention functioning; and 3) stakeholder workshop to confirm final programme theory, agree refinements and develop a delivery plan to operationalise refinements. All research was designed and conducted by the commissioned research team at Cardiff University. The team worked in consultation with Sam Dorney-Smith, an independent inclusion health nurse consultant with experience of designing and delivering an outreach intervention model. She was commissioned by Centre for Homelessness Impact (CHI) to provide the training component to nurses and support optimisation from a practice perspective. Study Setting and Recruitment The study was conducted in England. We purposively sampled three groups of national stakeholders to guide intervention description and refinement. Twelve professionals with experience of developing, delivering and/or funding outreach with a health specialism in the UK were sampled to participate in two professional stakeholder workshops. These professionals were identified by the intervention training provider (SDS), the intervention provider CGL, the funder CHI, and the research commissioner the Ministry of Housing, Communities and Local Government. Seven experts with lived experience were recruited to participate in one stakeholder workshop. These experts were members of the CHI Lived Experience Network. Twenty-three professional system stakeholders were purposively sampled to participate in semi-structured interviews, with a total of eight taking part. These were identified by individuals participating in the professional stakeholder workshops. They included professionals working in the statutory and voluntary sector, along with researchers with experience of working with homeless populations to understand service needs and experiences. Data Collection Rapid evidence review We reviewed the intervention manual, training materials and evidence-base to construct a candidate programme theory describing the following domains: mechanisms summarising how the intervention is intended to bring about change; components; implementation processes; targeted and potential unintended outcomes; and features of the context that will likely interact with mechanisms to modify intervention functioning. Grey literature specific to the intervention was identified through consultation with the intervention training provider (SDS) and the intervention provider CGL. We conducted a search of four bibliographic databases to identify prior models and evaluations of homelessness outreach delivered by health professionals: Scopus, CINAHL, PsycInfo, and MEDLINE. Search terms broadly mapped onto the population and intervention terms of PICO (Population, Intervention, Comparator, Outcome): ‘Homeless*’ AND ‘Nurse*’ AND ‘Outreach’. Searches were conducted in June 2024 and updated in March 2025. Professional stakeholder workshops We conducted one online workshop with all twelve professional stakeholders in June 2024 and a second workshop with seven of these stakeholders in November 2024. Both workshops were hosted on Microsoft Teams and facilitated by two members of the research team. The first workshop comprised a presentation on the candidate programme theory and was followed by a guided discussion of each domain, exploring the accuracy of our assumptions, addressing knowledge gaps, and identifying potential refinements. The second workshop included a presentation and discussion on the revised programme theory to reach agreement on its validity, confirm recommended refinements and agree a plan to operationalise them. Summary notes were taken of each workshop. Lived experienced stakeholder workshop We conducted an online workshop with people with lived experience of homelessness in November 2024. The workshop was hosted through Microsoft Teams and facilitated by two researchers, with support from a member of CHI staff. Discussion had a particular focus on exploring the context domain of programme theory (e.g. perceived contextual inhibitors of participation) and refinements to optimise intervention recruitment and acceptability. Summary notes were taken of the workshop. System stakeholder interviews We undertook semi-structured interviews with system stakeholders between November 2024 and January 2025. Interviews were conducted by a member of the research team via telephone or Microsoft Teams. They adhered to a pre-specified topic guide, with questions exploring understanding and experiences of the domains of programme theory (e.g. experience of proposed intervention components) and eliciting recommendations for refinements (Supplement A). Interviews were audio recorded in the relevant software platform, transcribed and redacted where appropriate, before being checked for accuracy. Data Analysis Candidate programme theory We extracted information from study reports identified from our rapid evidence review according to the a priori specified programme theory domains. The extant academic evidence-base had limited use, as descriptions of outreach models tended to lack a theoretical basis. Equally, a paucity of UK evidence meant a lack of insight into the localised contextual factors that might influence intervention functioning. In contrast, the grey literature was specific and sensitive to the review needs. As such we initially focused on extracting from the grey literature, drawing on wider research to verify our assumptions and address gaps in our theory. Where there were continued gaps in knowledge, we consulted with the intervention training provider (SDS), who was lead author on a large portion of the identified grey literature ( 13 – 15 ). This was notably helpful in unpacking some of the underpinning causal mechanisms that may drive intervention outcomes. From here we generated a slide deck to guide consultation, a narrative summary of the programme theory and an accompanying logic model. Refinement of programme theory Summary notes from the first professional stakeholder and lived experience stakeholder groups were analysed through content analysis, with codes derived from the programme theory domains. Coding was conducted by one researcher and then confirmed with the wider research team (RE, PM). We used thematic analysis to analyse system stakeholder data ( 24 ), with a priori parent codes mapping onto the domains of programme theory (e.g. interventions components) and child and grandchild codes theorising specific aspects of the domain. Recommendations for modifications were included as child/grandchild codes within each domain. Themes were generated based on the coding framework, with themes being tested through consideration of negative cases (e.g. examining the strength of support for specific recommendations across data sources, and if there was potential for harm). Coding was conducted by one member of the research team and checked by a second (RE, JW). We integrated findings from the two stakeholder workshops and system stakeholder interviews to generate a narrative summary of new knowledge for the programme theory, along with recommendations for refinements. While there were variations in the foci of data from each data source, they were largely consistent. We also developed a slide deck of key findings to support the final professional stakeholder consultation. Final programme theory and operational plan for delivery We undertook content analysis of the summary notes from the second workshop. Discussion points were integrated into the initial narrative description of the programme theory and associated logic model to generate a final programme theory. We also reported the final intervention using the Template for Intervention Description and Replication (TIDieR) checklist ( 25 ). For the recommendations, we constructed a slide deck summarising the recommendations and potential operational delivery plan. We subsequently hosted a meeting with CGL to share the operational plan (e.g. what needed to be included in their nurse training sessions) so they could take forward the necessary refinements. Ethical Considerations Ethical approval was provided by Cardiff University School of Medicine Research Ethics Committee (REF: 24/38). To protect the anonymity and confidentiality of participants in the study, we have not provided detailed information on socio-demographic or professional characteristics. Rigour and Reflexivity We achieved methodological rigour through a number of strategies. While sampling relied on a purposive approach, we recruited a range of stakeholders and participants, including those who identified as having more negative views of the outreach model. This was to ensure diverse data and the potential for negative cases. Consultations and interviews were audio-recorded, with the latter being transcribed and quality checked by a member of the research team. This ensured accuracy in representing data. Analysis of summary notes and interview data involved multiple members of the research team, ensuring credibility in interpretations. Having a clear research aim and design (e.g. intervention optimisation) that translated into a specified analytical framework (e.g. generating codes and themes linked to programme theory domains), offered a clear structure and transparent process. We maintained a highly sensitive approach to reflexivity throughout the study, reflecting on our positionality and power in relation to an underserved population. The research team met weekly to discuss and challenge interpretations and assumptions about the intervention. The research team regularly met with the intervention training provider (SDS) to ensure that data collection and analysis were grounded in the needs of practitioners, while responding to their real-world constraints. Throughout the process we adhered to recommended best practice in power sharing in health research ( 26 ). For example, in the lived experience stakeholder group consultation, we had clear definitions of roles and influence, inclusive facilitation, and stakeholder control over the nature and extent of engagement. RESULTS We present the results according to the three sequential phases of activity undertaken as part of the optimisation process: 1) development of candidate programme theory; 2) refinement of programme theory; and 3) confirmation of final programme theory and development of operational delivery plan. Candidate Programme Theory Our rapid review identified a total of 108 unique reports, comprising both grey literature and published research. We developed the candidate programme theory from these reports. Mechanisms We identified six central mechanisms through which the intervention should bring about change. Description of these mechanisms is presented in Table 1 . The extant academic literature provided limited theorisation of underpinning causal pathways, so mechanisms were largely generated through consultation with the intervention training provider (SDS). Mechanisms focused on the potential novelty of engagement with a nurse, and how it might open an opportunity for new conversations about health, social care and housing support. They extended to address professional identity, and how being a nurse could increase service users’ confidence in health care provision. There was also a focus on nurses’ knowledge and skills, and their unique capability to secure appropriate healthcare, which may motivate service users to engage. Nurse’s skills also included clinical and legal advocacy, and how they may be able to secure health, social care and housing provision based on their clinical and legal knowledge. Table 1. Causal mechanisms of outreach with a health specialism intervention Mechanism Description of Mechanism ‘Fresh’ engagement Nurses can introduce a ‘fresh’ engagement for people experiencing homelessness, which may increase the likeliness of taking part in a discussion about their needs. While this ‘fresh’ engagement focuses on health, it can open opportunities to have new and reframed conversations around housing and other social care needs, which might lead to engagement with housing services. a Outreach nurses’ trusted professional identity People experiencing homelessness may recognise the professional identity of nurses and trust their knowledge and advice. Service users may also recognise nurses’ professional responsibility around confidentiality, safeguarding and compliance, making them more willing to share their needs. a Reliant on nurses ability to organically build positive, trusting relationships through empathetic communication, compassion and trauma-informed approach. bcd People’s positive experience of a trustworthy and reliable health professional may increase engagement with other outreach services related to housing and potentially increase offers of appropriate accomodation. a Clinical and legal advocacy Nurses should possess clinical and legal knowledge. They should use this knowledge to advocate for the service user’s health, social care and housing needs. a As nurses undertake outreach in the places where people live, they will likely have a more holistic understanding of service users’ complex health needs than many other professionals, making them more effective at advocacy. d Identifying health care needs as an accommodation entitlement People who experience homelessness may not be owed a housing duty (e.g. people with No Recourse to Public Funds). However, having significant health care or support needs (e.g. self-neglect or serious brain injury), can activate a pathway to accommodation entitlement under the Care Act 2014. Nurses’ assessment of a significant health need can open up eligibility for accommodation b Appropriate service referral and engagement The clinical expertise of outreach nurses should ensure that service users are provided with accurate health assessments and referred to the health services that best meet their health needs. This might increase service users’ confidence in, and uptake of, health, social care and housing services. Nurses may also help to offer practical support to facilitate service access (e.g. arranging appointments, offering reassurance and preparing individuals for service engagement), which can further bolster confidence and engagement in the system. a Inter-professional recognition and relationships Nurses will likely have a shared expertise, language and ways of working with other health professionals, which may increase system responsiveness to their advocacy. a The fact that they are ‘speaking the right language’, means that other professionals will be more likely to recognise and act upon the identified need. bd . Nurses will likely have existing working relationships with other health professionals and can draw upon these relationships to support multi-agency collaboration. a The table reports the causal mechanisms underpinning the outreach with a health specialism intervention. The description of the mechanisms reports the source of the description: a Rapid evidence review, b Professional stakeholder workshop, c Lived experience workshop, d System stakeholder interviews. We generated an important mechanistic pathway to help explain one of the ways in which health and housing may be inter-related. Here we identified that people may have more immediate housing entitlements if they are identified to have a significant healthcare needs. Nurses’ engagement with service users’ might also increase the opportunity for Care Act 2014 assessments and Mental Health assessments, hence activating the pathway to accommodation entitlement. Target population For the purposes of this study, the funder pre-specified that the intervention should target individuals who are ‘living’ on the streets (defined as those seen sleeping on the streets on at least 6 separate occasions over a period of up to 6 months). The reason for this inclusion criteria was twofold. First, it is likely that people living on the streets will be better known to outreach services, therefore significantly increasing the likelihood of successful baseline and follow up data collection. Second, this subgroup of people rough sleeping is further away from being accommodated than peers who spend less time sleeping on the streets, and therefore the intervention has potential for greatest impact. Crucially for the pilot Randomised Controlled Trial, nurses will be permitted to support other people rough sleeping, but trial eligibility criteria will focus only on those ‘living’ on the streets. Components and implementation process : We described four intervention components to be delivered as part of the intervention. Description of the components, and their associated implementation process, is presented in Table 2 . These components were largely identified from the London model of outreach ( 13 – 15 ), while the activities to be undertaken as part of each component (e.g. services administered during outreach sessions) were derived from the wider evidence-base. Specified components were: training of outreach nurses to ensure knowledge and skill sufficiency; outreach shifts to engage with service users, meet immediate health needs, and motivate future service uptake; clinical supervision of nurses by a lead nurse to monitor wellbeing and quality assurance; and nurse support for service follow-up to ensure continued health, social care and housing uptake, often through participation in Multi-Disciplinary Teams (MDTs). Table 2 Components and implementation of outreach with a health specialism intervention Component Candidate programme theory Refinements for final programme theory Stakeholder recommendations and operational delivery plan Intervention principles Flexible and tailored approach. a Ensure explicit description of intervention as: flexible, responsive and person-centred bcd ; generalist b; and adopting a broad definition of rough sleeping. b See Key principles, skills and knowledge in outreach nurse training and Tailoring outreach to service users. Outreach nurse training Training will include a combination of standard and bespoke training. Standard Training : Standardised training modules will be made available to nurses through CGL. Training providers will include QNI, LNNM, Fairhealth and Aneemo. Bespoke Training : Nurses will receive a bespoke training package. Four half day training sessions will be delivered by the training provider (SDS). Two will be delivered online and two will be delivered in person. These will be complemented by a range of other electronic resources. a Need to include lived experience voices. c Knowledge and skill set should extend to include: (radical) safeguarding, mental health as a chronic disease (e.g. hoarding), management of common clinical conditions with discussions on clinical risk, communication strategies, reflective practice, cultural competence, and key legislation (e.g. housing law and the Care Act 2014). bcd Ensure nurses are trained in inclusive language. c Appoint nurses with requisite clinical and non-clinical skills. b Lived experience voices in outreach nurse training : Bespoke training modules to include training with individuals who have lived experience. This will focus on role-playing, so nurses can build confidence to engage with and support those with complex needs and a mistrust of healthcare systems. The training provider to design training modules to include activities that support lived experience input. Key principles, skills and knowledge in outreach nurse training : Bespoke training modules to be aligned with key principles. Training provider to ensure core training modules are aligned with these principles and deliver skills. Where there is limited time to cover all additional skill sets, CGL to ensure nurses undertake training CGL to construct job descriptions and appoint outreach nurses with demonstrable clinical and non-clinical skill sets that will enable them to work in accordance with intervention principles. Outreach shifts Nurses to accompany outreach workers on shifts approximately two days per working week (15–16 hours), offering direct support to service users. a Needs to be flexible in times, locations and seasons. bcd Focus on building sustained and trusting relationships. c Need reliable technology for accessing and recording information. d Tailoring outreach to service users : Nurses to be flexible in their approach. The training provider to ensure core training modules align with principles. Efficient data generation and flow : Nurses require appropriate and functioning equipment to undertake outreach. This includes technology to record service users’ health and medical equipment to meet immediate health needs. CGL to check and ensure that nurses have all required provision. Outreach nurse supervision Lead nurse to provide nurses with weekly clinical supervision. a Lead nurse to encourage reflective practice, so nurses can manage emotions, prevent burnout, process experiences and refine their approaches. c Lead nurse to coordinate and support continued programme of development. d Lead nurse can support if nurse reaches roadblock in advocacy. a Can coordinate a peer-led community of practice. a Tailoring outreach to service users : Nurses to be flexible in their approach. CGL to ensure supervision supports this tailored approach. Supportive supervision and community of practice : Supervision to have clear focus on supporting wellbeing of nurses to avoid burnout and monitor nurses use of reflective practice. CGL to construct job description and appoint lead nurse with skill set to support nurse wellbeing. CGL to support peer-led community of practice. Lead nurse to monitor nurses training needs. Service follow-up and Multi-disciplinary Team (MDT) meetings Nurses will need to follow-up with health, social care and housing services to ensure access to provision for the service users. May have to liaise with, organise and attend relevant MDT meetings to advocate for service user. Nurses need time for data entry and service follow-up. b Nurses need to attend follow-up appointments with service users and not just signpost them on. c Service-follow-up will often involve investigative work to ensure information is correct and complete so that continuous care it appropriate to the service users’s needs. b Different areas will have different infrastructures and different multi-disciplinary teams. Need to make sure nurses are not duplicating efforts but adding value. b Attendance at service user appointment : Nurses should have ability and capacity to attend appointments with service users, as signposting to follow-on services is largely ineffective. Training provider to emphasise this core training modules and CGL to ensure supervision encourages this as resources allow. Efficient data generation and flow : Data storge and sharing within delivery organisation and with other institutions needs to be addressed. CGL to monitor data flow throughout pilot study, working to ensure efficiency and tackle issues. Confidence and capability in service-follow up : To support service-follow up nurses need to feel confident to build relationships with health and non-health care sectors. They will require the skills to achieve this. Intervention developer to support confidence and capability in service follow-up during core training modules. CGL to encourage this skill through supervision, reflective practice and peer-led community of practice, identifying additional training where relevant. The table reports the components that comprise outreach with a health specialism intervention. The description of the components reports the source of the description: a Rapid evidence review, b Professional stakeholder workshop, c Lived experience workshop, d System stakeholder interviews. Outcomes : The funder pre-specified the primary outcome in the pilot Randomised Controlled Trial as the increased number of people moved off the street into appropriate accommodation. This is assessed by the CHI adapted version of the Residential Time-Line Follow-Back (RTLFB) survey. The secondary outcome is a health-related outcome, specified as Quality of Life and measured through the EQ-5D-5L. A range of additional outcomes were identified from the evidence-base for consideration in the present intervention model: number of health assessments; GP registrations and appointments; referrals to other services; service access and number of contacts; entry into specialised healthcare programmes such as detox; attendance at emergency departments; receipt of vaccinations and medications; and uptake of screening. Potential adverse, unintended outcomes were disengagement from a range of healthcare, social care and housing services. Context We identified eight initial features of the health, social care, and housing system, that may inhibit intervention functioning. Description of these context factors are presented in Table 3 . They include the diverse needs and socio-demographic characteristics of service users, organisational capacity, and the inter-professional data infrastructure available for delivering holistic and integrated care. Table 3 Context factors influencing functioning of outreach with a health specialism intervention Context Factor Description of Context Factor Complex service user needs Service users may have complex multimorbid health profiles and needs. There may also be specific communication needs such as: literacy; learning difficulties; mental health problems; complex psychological trauma; acquired brain injury; limited capacity; neurodiversity; and addiction. a Language and cultural competency Approximately 20% of service users can require an interpreter for communication. It can be difficult to provide this on the streets due to background noise and it not being ideal to pass the phone between the service user and nurse. b Geographical location of service users Service users may be located across a wide geographical area and nurses might spend a significant time travelling. Densely populated inner city areas may not be easily accessible by cars and alternative methods of transport are needed. a In rural areas, homelessness is more likely to be hidden and service users more difficult to locate. d . There may be boundary issues, and having a transient population that moves between areas can make it difficult to provide continuous care. bc It may be re-traumatising for service users to recount their histories, leading to disengagement. c Profile of service user population b The composition of the homeless population will vary by area. In some areas there may not be a large population of people who sleep rough, and so there may be a low rate of intervention eligibility. However, there may be a large portion of people who are based in hostels, and the intervention will not be able to meet their needs as they are ineligible for support. b Belief systems and discourse around homelessness Outreach nurses, and the wider health, housing and social system, may hold belief systems that are not supportive of the intervention. For example, they may not agree with the principles of harm reduction or have negative or unhelpful attitudes towards people who sleep rough. abcd Organisational capacity There may be challenges in recruiting nurses with sufficient skill sets, especially in non-urban areas. b There may be a lack of capacity in outreach teams to accompany nurses during an outreach shift. ab, Nurses will be required to undertake out-of-hours working, and they may not be outreach teams available to support this. b Nurses may experience burnout where this is limited organisational capacity to offer them support and supervision. c Professional expertise and credibility Nurses may not have the requisite baseline experience and expertise to navigate the health and housing system, and the intervention training may not be sufficient to ensure they are fully upskilled. They also might not have the requisite professional standing in the health, social care and housing system to advocate for change. This can be particularly challenging where nurses do not have an NHS registered account from which to email. Having a registered email account can help to emphasise shared working culture and practices between health professionals. a System legal literacy and compliance There may be a lack of legal literacy and compliance within the health, social care and housing system to ensure a response to nurses’ assessments. For example, local housing providers may not be aware that they there is a safeguarding assessment entitlement for someone who has been classified as experiencing ‘self-neglect’, and this could lead to alternative offers in terms of housing. Professionals (e.g. G.P. practices) may not share information with nurses due to perceived compliance with legal frameworks that state information cannot be shared without a signed consent form. Record generation maintenance and data sharing infrastructure People who experience homelessness can be a transient population, and there needs to be a centralised system for sharing data between areas. c There are issues with recording and sharing of information between professionals, as health, social care and housing providers may employ different recording systems, with different legal and security requirements. a Nurses may experience challenges in generating data records during outreach shifts if there is no consistent reporting template, a lack of secure back-up, poor signal and technological problems. abd Availability of services in wider system bcd Outreach provision will likely involve referral to other service providers. There may not be accessible and efficient referral routes, or the length of time that a referral takes may encourage disengagement. c The level of provision will vary by area, for example the availability of immediate care following a hospital discharge. b Some service users may not have the resources to attend services if the only available provision requires use of public transport. c The table reports the context factors that might influenced the functioning of the outreach with a health specialism intervention. The description of the context factors reports the source of the description: a Rapid evidence review, b Professional stakeholder workshop, c Lived experience workshop, d System stakeholder interviews. Refinement of programme theory We refined the programme theory and generated initial recommendations for optimisation through the professional and lived experience stakeholder consultations and system stakeholder interviews. Overall, participants confirmed our candidate programme theory, and there were no requirements to modify our description on the basis it was incorrect. Discussion and data focused on adding additional knowledge to deepen our understanding. Mechanisms All participants agreed the relevance of the proposed mechanisms, although there was consideration that three key mechanisms would leverage more causal power when targeting outcomes. No new mechanisms were identified. First, both stakeholder groups and system stakeholder interviews emphasised the importance of the mechanism related to professional identity, and service users’ willingness to trust their knowledge and advice. However, stakeholders stated that this trust could not simply be obtained from a professional title, but was contingent on nurses’ ability to build rapport, provide empathetic communication, and draw on a trauma-informed approach. Lived experience stakeholders emphasised the profound mistrust some individuals experiencing homelessness have of healthcare providers due to prior discriminatory treatment. They claimed that nurses would have to work to overcome this perception by affirming service users’ dignity and value. This was also recognised by system stakeholders who cited the challenge of building trust: It's, it's difficult for us to build up that trust with someone anyway, isn't it? But someone that maybe has got a health focus that someone isn't quite ready to address, that or is scared or petrified of going into hospital would be a big challenge. So again, for us, we quite often we've got young people that are quite poorly but absolutely petrified of going to hospital. (System Stakeholder 8: Team leader, Homeless Shelter) Second, the professional stakeholder group and system stakeholders cited the importance of the advocacy mechanism, highlighting the need for nurses to advocate for service users’ rights. One system stakeholder offered an extended account of how outreach made nurses better placed to advocate for a service user as they had a holistic and more realistic understanding of their health complexities and needs, as compared to hospital-based professionals: So for instance, if you look at a Mental Capacity and, and if you look at the Care Act, it's very prescriptive and someone can be in a hospital bed or wherever and, and things look great because you know the nurses are there and they’re (service user) active. You live in, you know, they've got a nice clean bed, and the food is brought to them and everything's looking, looking, OK, you know, ready for that discharge. But you go out to rough sleeping. All of those things and not, and just not achievable and that person cannot cope in that environment, so having, having eyes on the site and what's going on in real time at the location. Definitely informs how you then put that case forward and, and I don't know, bringing all the health-related things together. And presenting that in a way that explains that because the person themselves can't explain… (System Stakeholder 5: Homeless Health and Clinical Lead) Third, professional stakeholders and system stakeholders reported that interprofessional relationships were key to achieving the integrated and holistic approach to care that would be needed to effectively support service users. Professional stakeholders emphasised the importance of ‘speaking the same language’. Components and implementation process Stakeholders from all sources agreed with the four intervention components and the proposed implementation process. No additional intervention components were identified as being needed to activate the causal mechanisms. Principles A central feature of discussion across stakeholders was the principles needed to underpin the intervention. Participants emphasised the need for a flexible, inclusive, responsive, person-centred model, while balancing this with consistency to ensure equitable delivery across diverse areas and service users. There should be focus on responding to localised gaps in current outreach provision. Discussion extended to consider the target population. While there was agreement that individuals experiencing rough sleeping should be prioritised as they will likely have higher health needs, stakeholders felt the definition of rough sleeping needed to include those who are not visible on the streets. This includes those who live in tents, intermittently stay in hostels, or rely on other unstable living arrangements. Professional stakeholders also stated that healthcare provision should focus on generalist care that aligns with a primary care approach. To this end, nurses should be focused on initial assessment and services, with referral to specialist providers for further treatment. This reinforces the need for strong multi-sectoral collaborations. Outreach nurse training This component was the focus of stakeholder discussion across sources. Lived experience stakeholders maintained that individuals with lived experience should be central to the design and delivery of training. This ensures nurses are exposed to real world scenarios and can foster deeper understanding and preparedness. Such an approach is particularly important for nurses with no prior experience of working with individuals experiencing homelessness. There was extensive comment on ensuring knowledge and skill development. Nurses should be trained in clinical and non-clinical skills related to: clinical risk management; unconscious bias; trauma-informed care; (radical) safeguarding; legal advocacy; supporting individuals with diverse needs (e.g. additional learning needs, autism and serious brain injuries), different age groups (e.g. young people), different gender identities, different cultural backgrounds, and different clinical conditions. Lived experience stakeholders observed a central barrier to service engagement is the use of complex, bureaucratic and condescending language, including terms such as ‘self-neglect’ and ‘failed to attend’. To enact the mechanism around trust, stakeholders also emphasised the need to train nurses in empathetic approaches. Outreach with health specialism shifts All stakeholder groups stressed the importance of outreach shifts being tailored to the needs of local populations, offering care at varied times, locations and seasons. As part of this flexible approach, they also indicated the need to use various transport methods (e.g. bicycles and vans) to enhance mobility, accessibility and reach. Lived experience stakeholders stated the need for accessible outreach locations, including community hubs such as soup kitchens or hostels, so that service users feel comfortable. Specifically related to the mechanism of professional identity, lived experience stakeholders highlighted the need for nurses to build a sustained and trusting relationships with service users over time. This is to be achieved through consistent and repeat contact where viable. System stakeholders were notable in highlighting implementation barriers that would need to be anticipated, including having technology that would reliably work and access information They (service users) might have set themselves up in an area that's difficult to find. So if people are using substances or if they have impaired memory then it can be challenging to get kind of an accurate history from people, and so a big challenge can be if you, if you're how much you can help somebody. If you can't see their health notes and records. And so the IT how, how you link in you know on it if you are out and about on the street. That's a big a big challenge as well. (System Stakeholder 4: Nurse Practitioner) Supervision of outreach nurses Lived experience stakeholders identified the need for supervision to encourage and support reflective practice, so that nurses are able to manage emotions, process experiences, prevent burnout and refine their approaches. System stakeholders also indicated the need for a continued development programme, which may be coordinated and supported by the lead nurse. Service follow-up and MDT meetings All stakeholders recognised the necessity of embedding nurses in MDTs to ensure services are addressing the interconnected needs of health, social care and housing. It was noted that nurses may need to build their confidence to undertake this role. Outcomes The pre-specified primary and secondary outcomes were identified as being appropriate by participants given the components and underpinning mechanisms. Additional outcomes identified in the evidence-base were confirmed and distilled to the most important (see Fig. 1 ). Primarily discussed within the professional stakeholder workshop and system stakeholder interviews, stakeholders cited the importance of an integrated approach that tackles both housing and health care due to their causal interconnectedness. Tackling health conditions may encourage housing stability, while appropriate accommodation will improve capacity to prioritise health. As one system stakeholder noted: Obviously the health and the housing and the benefits and everything is very linked up and it's got to be that holistic approach because that's why the people have ended up on the street because they've lost the links of all of those things and you can't do one without the other. (System Stakeholder 6: Nurse Practitioner) Stakeholders recognised unintended outcomes that might be considered as part of subsequent piloting, evaluation and implementation. These were the risk of creating dependency on outreach services for health support, which may later lack capacity. This could happen if transitions to mainstream healthcare services are not well managed. Context All stakeholder groups acknowledged the initial eight context factors that might inhibit intervention functioning, while focusing discussion on four. These were not necessarily deemed more important, but rather needing additional in-depth description. An additional two context factors were identified. First, the context factor of geographical location of service users. In addition to the geographical dispersal of individuals within a service area, lived experienced and professional stakeholders explained the complications with them moving between areas. In such instances, they might move outside of the boundaries of certain health, social care and housing providers, making it impossible to ensure continuous provision. Equally, having individuals repeatedly recount their needs and histories may be re-traumatising, potentially leading to service disengagement. Second, was the context factor related to belief systems and discourses around homelessness. Professional stakeholders noted how people experiencing homelessness are stigmatised across the health care system, notably in hospitals. There are also complications where discourses differ between professional groups, which might inhibit interprofessional collaboration. As one system stakeholder stated: There can be tussles between different professional groups within the statutory sector, you know, there may not be similar ideas or understanding about risk or thresholds or pace of response… (System Stakeholder 2: Homelessness Researcher) Third, was the organisational capacity context factor. There is the potential not to recruit sufficiently qualified nurses, especially where there is a concentration in expertise in urban areas (e.g. London), and less of a potential workforce in more rural areas. Lived experience stakeholders raised concerns about the possibility for nurses to experience burnout during intervention delivery. They highlighted the emotional toll of supporting individuals who have experienced high levels of trauma, and managing mental health crises and other complex health and social needs. With limited organisational capacity to provide ongoing support, nurses may feel overwhelmed, leading to high staff turnover. Fourth, was the record maintenance and data sharing infrastructure context factor. Lived experienced stakeholders highlighted that population transience, such as the above trend for moving between areas, meant that data needed to be accessed by a range of professionals. However, there is often a lack of detailed and centralised record-keeping to support service continuity. System stakeholders maintained that IT infrastructure would need to be improved to ensure effective data sharing. The first new context factor was considered by the professional stakeholder group. This was the profile of individuals experiencing homelessness, and the fact that different intervention delivery areas may serve different populations. As such it could be difficult to deliver the intervention if the eligibility criteria were restricted to particular groups (e.g. rough sleeping), as this may place many in need service users out of scope. The second novel context factor, reported across all data sources, was the availability and accessibility of service provision in the wider health, social care and housing sectors. Lived experience stakeholders noted that nurses might signpost and refer service users to mainstream healthcare but were adamant that this was not helpful: it makes people feel they are being “gotton rid of”. They felt that where individuals live in precarious conditions, immediate needs take precedence, meaning continued engagement with a referral process may not be viable. All stakeholder groups felt nurses should be able to attend appointments with service users. There were related concerns about limited resources to attend appointments where services are only available in locations reachable by public transport, or if they require access to digital tools such as smartphones. This context factor is also relevant to discussion regarding the intervention outcome. Professional stakeholders and system stakeholder interviews recognised that in some areas, variations in service availability and community resources would likely influence whether nurses targeted health or housing outcomes, leading to inconsistency in practice across areas. Final programme theory and operational delivery plan We integrated findings from the refinement of programme theory phase into the candidate programme theory to generate the final programme theory. Overall professional stakeholders agreed with the final programme theory as an accurate description of how outreach with a health specialism should optimally work. Stakeholders also made some further clarifications to our understanding of the context factors, which are included in Table 3 . We distilled findings to identify seven refinements to intervention components and implementation processes that will maximise the likelihood of specified mechanisms being activated. These were accompanied by an operational delivery plan. Professional stakeholders agreed with these recommendations. Only small points of clarification and additions were made. It is important to note that stakeholders provided few recommendations for modifying the context during the refinement of programme theory phase. Rather they focused on how the intervention could be changed to maximise functioning within system constraints. This may have been due to a perception that context factors could not be restructured as they are beyond the scope of the intervention team. Equally, stakeholders were not always clear exactly how context factors would interact with the intervention, and so articulating the exact modifications needed was a challenge. It may be easier to develop recommendations for contextual restructuring following the piloting phase, when we have empirical evidence as to how these interactions unfold. The final recommended intervention refinements, and plan to operationalise them, were: Lived experience voices in outreach nurse training Bespoke training modules to include training with individuals who have lived experience. This will focus on role-playing, so that nurses can build confidence to engage with, and support, those with complex needs and a mistrust of healthcare systems. Training provider (SDS) to design training modules to include activities that support lived experience input. Key principles, skills and knowledge in outreach nurse training : Bespoke training modules to be aligned with key principles of: trauma-informed care (‘meet people where they are’); building trust rather than dependence; empathy and understanding; tailoring provision to meet diverse needs; avoiding authoritarian language; and working in ways that prevent burnout. Key knowledge and skills learning to be included: (radical) safeguarding, mental health as a chronic disease (e.g. hoarding), management of common clinical conditions with discussions on clinical risk, communication strategies, reflective practice, cultural competence, and key legislation (e.g. housing law and the Care Act 2014). Training provider (SDS) to ensure core training modules are aligned with these principles and deliver skills. Where there is limited time to cover all additional skill sets, CGL to ensure nurses undertake training modules from portfolio of options available via the Queen’s Nurses Institute, the London Network of Nurses and Midwives, Fairhealth and Aneemo. CGL to construct job descriptions and appoint outreach nurses with demonstrable clinical and non-clinical skill sets that will enable them to work in accordance with intervention principles. Supportive supervision and community of practice Supervision to have clear focus on supporting wellbeing of nurses to avoid burnout and monitor nurses use of reflective practice. CGL to construct job description and appoint lead nurse with skill set to support nurse wellbeing. CGL to facilitate relationships between outreach nurses to build a supportive peer-led community of practice with knowledge and skill exchange. Lead nurse to monitor nurses training needs and support uptake to ensure continued capability and competency in role. Tailoring outreach to service user needs Nurses to be flexible in their approach. This includes being geographically mobile, visiting spaces that are safe and convenient for people who sleep rough, and adapting to the specific needs of each service user. The training provider (SDS) to ensure core training modules support flexibility. CGL to ensure supervision supports this tailored approach. However, core training, additional training and supervision must emphasise the need for some standardisation and parameters to ensure consistency, making sure nurses are working in accordance with the intervention’s underpinning causal mechanisms. Efficient data generation and flow Nurses require appropriate and functioning equipment to undertake outreach. This includes technology to record service users’ health and medical equipment to meet immediate needs. CGL to check and ensure that nurses have all required provision. Data storge and sharing within delivery organisation and with other institutions needs to be addressed. CGL to monitor data flow throughout pilot study, working to ensure efficiency and tackle issues. Attendance at service user appointments Nurses should have ability and capacity to attend appointments with service users. Training provider (SDS) to emphasise this in core training modules and CGL to ensure supervision encourages this as resources allow. Confidence and capability in service-follow up To support service-follow up nurses need to feel confident to build relationships with health and non-health care sectors. Training provider (SDS) to support confidence and capability in service follow-up during core training modules. CGL to encourage this skill through supervision, reflective practice and peer-led community of practice, identifying additional training where relevant. On confirmation of the final programme theory, we agreed with the training provider (SDS) and CGL that the proposed modifications to the intervention components and implementation process would be viable. This was partly because proposals harnessed a large amount of existing resource from the wider infrastructure, for example accessing training modules from CGLs own catalogue or national nursing training networks. The final agreed programme theory is presented in Table 4 , in accordance with the TIDieR checklist and the associated logic model (Fig. 1 ). Table 4 TIDieR description of outreach with a health specialism intervention TIDieR Framework Component Description Brief Name: Provide the name or a phrase that describes the intervention Outreach services with health specialism for people rough sleeping. Why: Describe any rationale, theory, or goal of the elements essential to the intervention The overarching rationale of the intervention is that nurses meet service users where they are rough sleeping, which increases contact with service users. Nurses have a respected identity as a health professional that service users may trust to support them. This trust can be enhanced by nurses having professional knowledge to identify and deliver the correct service provision and have the expertise and professional standing to secure service access. Nurses should be able to use clinical and legal literacy to advocate for the service user. Nurses’ identification of a health care need for service users can also ensure access to appropriate accommodation, as health care needs can result in an accommodation entitlement. Multidisciplinary collaboration between nurses and other sectors can help to identify and secure appropriate follow-on services. What (Materials): Describe any physical or informational materials used in the intervention, including those provided to participants or used in intervention delivery or in training of intervention providers. Provide information on where the materials can be accessed (such as online appendix, URL) Training to include a combination of standard and bespoke training. Standard Training : Standardised training modules will be made available to nurses through CGL. Training providers will include QNI, LNNM, Fairhealth and Aneemo. Bespoke Training : Nurses will receive a bespoke training package. Four half day training sessions will be delivered by the training provider (SDS). Two will be delivered online and two will be delivered in person. These will be complemented by a range of other electronic resources. a Training to include lived experience voices. c Knowledge and skill set should extend to include: (radical) safeguarding, mental health as a chronic disease (e.g. hoarding), management of common clinical conditions with discussions on clinical risk, communication strategies, reflective practice, cultural competence, and key legislation (e.g. housing law and the Care Act 2014). What (Procedures): Describe each of the procedures, activities, and/or processes used in the intervention, including any enabling or support activities Principles : Intervention to be flexible, responsive, person-centred, generalist, and adopt a broad understanding of rough sleeping. There are four key intervention components: Outreach nurse training : Includes standard and bespoke training. Outreach with health specialism shifts : Outreach nurses accompany outreach teams to deliver healthcare on the street and arrange access to follow-on services. Outreach nurse supervision : Clinical supervision of nurses by a lead nurse. Service follow-up and Multi-disciplinary Team (MDT) meetings : Arrangement of follow-up healthcare and housing services after outreach shifts. Accompany service users to meetings if viable and appropriate. Attendance at MDT meetings to advocate for the service user. Who provided: For each category of intervention provider (such as psychologist, nursing assistant), describe their expertise, background, and any specific training given Lead nurse Lead nurse to be based in CGL (equivalent to top NHS Band 8). Will line manage and supervise the trained outreach nurses (equivalent to top NHS Band 7). Lead nurses will provide clinical supervision and personal support to nurses. Outreach nurses Desirable competencies for the outreach nurses include: ● An advanced assessment course and/or significant experience of clinical triage e.g. within an A&E department; ● History of working with people who have experienced homelessness; ● A proven ability to assess and manage clinical risk independently; ● Level 3 safeguarding training (including an understanding of self-neglect); ● Ability to directly prescribe (i.e. the ability to provide an immediate prescription) or to provide drugs by Patient Group Direction. Based on previous case examples of outreach nurses, it has been suggested that they should be an NHS Band 7 equivalent to ensure they have the requisite experience and expertise (Dorney-Smith, N.D.). Outreach nurse training Standard training : Training will be facilitated by CGL and primarily provided through the QNI, LNNM, Fairhealth and Aneemo. Bespoke training : Training will be developed by training provider (SDS) and hosted by CGL. Outreach teams Typically 1–2 members of the designated outreach team will accompany the nurses during the outreach shifts. The number of accompanying outreach workers can be negotiated, but the key is that outreach nurses should not go alone. Other professionals (for MDT meetings) A range of partnering teams and professionals will be required to ensure that service users’ complex needs can be met, and appropriate follow-on care can be planned. These can include, but are not limited to (Dorney-Smith, 2022): ● Local Authority rough sleeping pathway teams and their leads ● Local Authority housing teams ● Linked GPs and other primary care services ● Outreach and mainstream mental health teams ● Outreach and mainstream addictions teams ● Social care teams / Safeguarding teams including specialist Social Workers ● Police and Police Community Support Officers, transport police and security ● Parks attendants ● Various voluntary sector support services e.g. day centre providers How: Describe the modes of delivery (such as face to face or by some other mechanism, such as internet or telephone) of the intervention and whether it was provided individually or in a group Outreach nurse training : To be delivered in person and online. Outreach with health specialism shifts : To be delivered in person mainly on the street. Data entry and storage to be done electronically. Outreach nurse supervision : To be delivered in a group or individual format online or via telephone. May entail occasional in-person meetings. Service follow-up and MDT meetings : To be delivered online, via telephone or in person depending on the services that outreach nurses follow-up with or the meetings they attend. Where: Describe the type(s) of location(s) where the intervention occurred, including any necessary infrastructure or relevant features Outreach nurse training : Will be remotely delivered and accessed through the relevant platform. The venue for in-person training to be agreed. Outreach with specialism shifts : Will be delivered mainly on the street. Outreach teams will identify the location of the service users as they will have more experience and knowledge of their location. Nurses may attend other venues (e.g., soup kitchens) and health settings to enrol participants, facilitate follow-on care, or track participants. Outreach nurse supervision : Online meetings will be remotely accessed through the relevant platform. The venue of in-person meetings will likely be at CGL offices. Service follow-up and MDT meetings : Online meetings will be remotely accessed through the relevant platform. In-person meetings will likely be accessed at the location of the services that outreach nurses follow-up with. When and how much: Describe the number of times the intervention was delivered and over what period of time including the number of sessions, their schedule, and their duration, intensity, or dose Outreach nurse training Standard training : Training to be made available to outreach nurses on an ongoing basis. CGL will arrange a hosting platform and training developer will share resources to be hosted alongside training modules provided by the Queens’s Nursing Institute, LNNM, Fairhealth and Aneemo training and resource platforms. Bespoke training : Training to be delivered as four half day sessions. Two to be delivered online and two to be delivered in person. Nurses working week will be split as follows: Outreach with health specialism shifts (40% of week) :This should include a minimum of two shifts on the streets with service users, each take approximately seven to eight hours (approx. 15–16 hours total). Outreach teams will need to be flexible at times providing out-of-hours care as service users can have transient schedules. Outreach nurse supervision (20% of week) : Lead nurse to meet with the outreach nurses collectively on a weekly basis. Each nurse will also have monthly (where possible) clinical supervision meetings with the lead nurse. Lead nurses across LAs may benefit from meeting regularly to share good practice and support. Additional community of practice activities to be considered during this time. Service follow-up and MDT meetings (40%) : Nurses to ensure data and information are complete and to secure follow-up services. They may also be required to spend time attending MDT meetings. Where viable, nurses may accompany service users to meetings. Nurses also to spend time completing data collection for the pilot cluster Randomised Controlled Trial. Tailoring: If the intervention was planned to be personalised, titrated or adapted, then describe what, why, when, and how The intervention should always comprise delivery of the four components. In accordance with intervention principles, delivery should be flexible to meet the needs of individual service users and focus on responding to localised gaps in current outreach provision. Nurses should be aware of underpinning causal mechanisms to ensure any tailoring does not compromise intervention functioning. Modifications: If the intervention was modified during the course of the study, describe the changes (what, why, when, and how) To be reported after completion of the pilot Randomised Controlled Trial. How well (Planned): If intervention adherence or fidelity was assessed, describe how and by whom, and if any strategies were used to maintain or improve fidelity, describe them Key fidelity measures to include: Outreach nurse training ● Completion of standard and bespoke training. Nurse outreach with health specialism shifts ● Delivery in outreach settings for approximately 15–16 hours per week over two shifts ● Service user uptake of treatment/support offer ● Delivery of immediate treatment (where appropriate) ● Manageable caseloads Outreach nurse supervision and quality assurance ● Number of supervision sessions between Lead Nurse and nurses Follow-up services and MDT meetings ● Number and range of follow-up services secured for service users (where appropriate) ● Uptake of follow-up service offer by service users ● Number of MDT meetings attended by outreach nurses How well (actual): If intervention adherence or fidelity was assessed, describe the extent to which the intervention was delivered as planned To be reported after completion of the pilot Randomised Controlled Trial. DISCUSSION In the present study we report one of the first systematic and empirically-driven descriptions of outreach with a health specialism. We have comprehensively described the intervention’s programme theory, eliciting the causal mechanisms, components, implementation processes, outcomes and context. This is an important contribution, as while outreach has been recommended by NICE guidance ( 12 ), currently there is limited understanding of how the intervention should work or how it might interact with system characteristics in the generation of outcomes. In the study, we also identified several recommendations for refining components and implementation processes to optimise functioning. Summary of findings We identified six mechanistic pathways through which outreach with a health specialism should bring about change. These mechanistic pathways target both housing and health outcomes. For example, outreach nurses may draw upon their legal literacy and advocacy skills to establish an accommodation entitlement based on their service users’ health status. This targeting of multiple inter-related outcomes is vital due to the extensive evidence supporting the bi-directional relationship between housing and health in homeless populations. Individuals with poor health outcomes, such as an acquired brain injury, are less likely to obtain stable housing ( 27 ). Meanwhile, a focus on meeting physiological needs, such as shelter, can ensure healthcare uptake is prioritised ( 6 , 8 ). As part of the study, we optimised intervention components and implementation processes. Central to the refinement process was extending the knowledge and skill base of nurses to ensure competency in working with a range of people with different characteristics and experiences of health and housing services. Strengthening confidence and capability in service-follow up and engagement with other health, social care and housing services was also key. This is justified by a recent evaluation of different healthcare models for supporting outcomes for individuals experiencing homelessness ( 28 , 29 ). The study found that mobile outreach teams often struggled with collaborative working, leading to uncertainty and confusion among patients and low levels of continuity in care. However, where GPs were part of the mobile team, and care provision across health professionals was fully integrated, continuity in care rates were higher. We also identified that outreach provision would need to be flexible and tailored to achieve acceptability among service users. This is supported elsewhere in the evidence-base ( 28 ). We generated context factors that may inhibit intervention functioning. Given that much of the existing research on outreach is from the USA and Australia, these findings offer a significant contribution to the more limited understanding of how the wider health, social care and housing system could influence the effectiveness of health outreach in the UK ( 18 , 19 ). Key context factors include variations in population characteristics, limited organisational capacity, and availability of follow-on services. As noted, stakeholders generally did not focus on restructuring the context during recommendations for refinements, rather describing them as entrenched barriers. It is important to consider further how these context factors can be effectively tackled, amidst calls for intervention efforts to be supported by upstream re-structuring ( 30 ). Implications for policy and practice The findings of the study, combined with the subsequent pilot cluster Randomised Controlled Trial, will provide important learning to help inform future policy-making and practice. Our optimised model provides a mechanism for realising NICE and NHS Long Term Plan recommendations for an integrated, multidisciplinary approach to mitigating health inequalities ( 12 , 31 ). Importantly, we have shown how the intervention might target the dual outcomes of health and housing, both of which are key policy priorities for this population ( 12 , 32 ). To support this type of approach moving forward, there is an imperative need for workforce development, particularly in terms of the training and retention of nurses with advanced clinical and legal competencies, a sentiment that aligns with the Queen’s Nursing Institute ( 33 ) proposal for specialist training in inclusion health. The study further provides useful implications for practitioners. A central thread of our findings was the need to foreground the voices of lived experience individuals in training and delivery to ensure professionals can meet complex and diverse needs. This resonates with NICE guidelines for people experiencing homelessness, which recommend co-production in service design ( 12 ). We also recognise the need for tailoring services to the need of target populations. However, this needs to be undertaken within specified parameters, and there is value in having practitioners be familiar with the underpinning mechanisms of interventions, so they are aware when local modifications are compromising the programme theory and risking outcomes. Finally, to support integrated and inter-professional care, nurses need to be trained and empowered to engage in the complex health, social care and housing landscape, receiving ongoing supervision and training as required. Implications for future research The study has important research implications. It offers a worked case example of how interventions can be optimised, and the value of optimisation in maximising the likelihood of an intervention functioning. While optimisation is clearly defined and operationalised within optimisation research designs such as MOST ( 34 ), there is less understanding of how optimisation fits with other evaluation frameworks. We have demonstrated how optimisation can be undertaken as part of the first phase of the Medical Research Council guidance on the development and evaluation framework ( 16 ). There is a need to continue to make methodological progress on how to conduct optimisation in alignment with the guidance, potentially with a view to developing frameworks similar to those that have been produced for intervention development ( 35 ). In terms of the outreach with a health specialism intervention, there is an ongoing need to strengthen the evidence-base. This will be partly addressed by the pilot cluster Randomised Controlled Trial that follows this optimisation study. Future research needs to focus on testing the causal power of the mechanisms we have proposed, identifying additional mechanisms, and examining if these mechanisms may generate unanticipated and even harmful outcomes alongside the intended impacts. Relatedly, further work is required to establish the full complement of outcomes that are theoretically appropriate for this intervention approach. This includes building evidence of effect sizes for different outcomes. It also means generating process evaluation data to understand if local systems and stakeholders can simultaneously target multiple outcomes or if they tend to deliver the intervention in a way that prioritise certain impacts (e.g. healthcare uptake rather than appropriate accommodation). Finally, as a central principle of the intervention is to achieve flexibility and tailoring, there needs to be a focus on using appropriate methods for defining and evaluating non-standardised approaches. The growing literature on adaptive and just-in-time adaptive public health interventions may be supportive here, along with frameworks for assessing fidelity to mechanisms rather than components ( 36 , 37 ). Strengths and limitations There are a number of strengths and limitations that should be taken into account when interpreting the study findings. The study benefited from a range of stakeholders engaged across the homeless sector in the UK, including those with lived experience. This enabled us to generate rich insights into the intervention delivery context, particularly from system stakeholders who had a history of implementation. We would have benefited from further involvement of lived experience stakeholders, as the contribution of participating individuals was extremely useful. We will continue to prioritise understanding their experiences of intervention participation during the process evaluation embedded in the pilot trial. The study was further strengthened by the sequential and integrated approach to data collection, where findings from each stakeholder group could feed into discussion with the next. This allowed us to explore consistencies and discrepancies in understanding and views between stakeholder groups. It was particularly useful to return to the stakeholder professional group to confirm the final programme theory, as we were able to verify if the intervention description and optimisation process had accurately responded to feedback. We would have benefitted from confirming the final programme theory with lived experience and system stakeholders, but unfortunately time did not allow. CONCLUSION Outreach has been recommended by NICE guidance as a potentially effective approach for targeting healthcare uptake among individuals experiencing homelessness. In this study we described and optimised the programme theory for outreach with a health specialism, identifying the causal mechanisms which explain how the intervention may target both health and accommodation. A comprehensive description of the programme theory is important for future evaluation, as it clarifies the intervention that evaluators are making evidence-based claims about. Our recommendations for optimising intervention components and implementation processes will support nurses and other professionals in developing, implementing and adapting interventions for delivery with individuals experiencing homelessness. Declarations Ethics approval and consent to participate Ethical approval is provided by Cardiff University School of Medicine Research Ethics Committee (REF: 24/38). Informed consent was obtained by individuals participating in system stakeholder interviews. The study was conducted in accordance with the Declaration of Helsinki. Consent for publication Not applicable. Availability of data and materials The Ministry of Housing, Communities and Local Government (MHCLG) is the “data controller”. The privacy notice for the study is reported here: https://www.gov.uk/government/publications/homelessness-and-rough-sleeping-outreach-with-a-health-specialism-privacy-notice/homelessness-and-rough-sleeping-outreach-with-a-health-specialism-privacy-notice#storage-security-and-data-management. Further information about data availability can be obtained by contacting the MHCLG. Competing interests Sam Dorney-Smith was commissioned by the Centre for Homelessness Impact as an Independent Advisor to the Test and Learn Programme. She supported the delivery of stakeholder workshops. She was funded through Inclusion Nursing to deliver the training component of the intervention. Funding was not contingent on the content or implementation strategy of the training components, which were partly developed and refined through the optimisation workshops. Funding This work has been funded by the Ministry of Housing, Communities and Local Government (MHCLG) via the Centre for Homelessness Impact (CHI) as part of the Test & Learn and Systems-Wide Evaluation Programme, a £15m programme of work to improve the evidence base and understanding of what works to end rough sleeping. Clinical Trial Number ISRCTN11572394 (13/12/2024) Authors' contributions R.E., P.M., L.A., Y.M., R.B., and J.W. led the conceptualisation and design of the study. R.E., P.M., L.A., S.D.S. and J.W. led the acquisition of data, analysis of data and interpretation of data. R.E. led the drafting of the manuscript. All authors reviewed the manuscript, revising it critically for important intellectual content. Acknowledgements The authors are grateful to all stakeholders who have contributed to the study. We are grateful to Christopher Usborne, Centre for Trials Research, School of Medicine, Cardiff University who has provided professional service support for the study. References Fornaro M, Dragioti E, De Prisco M, Billeci M, Mondin AM, Calati R, et al. Homelessness and health-related outcomes: an umbrella review of observational studies and randomized controlled trials. BMC Med. 2022;20(1):224. Aldridge RW, Story A, Hwang SW, Nordentoft M, Luchenski SA, Hartwell G, et al. Morbidity and mortality in homeless individuals, prisoners, sex workers, and individuals with substance use disorders in high-income countries: a systematic review and meta-analysis. Lancet. 2018;391(10117):241–50. White J, Moriarty Y, Lau R, Cannings-John R, Palmer A, Weightman AL et al. Homelessness, type of homelessness, and risk of cause-specific mortality: a systematic review and meta-analysis of 116 studies comprising 2,563,633 homeless people and 129,292,553 population controls. Preprint. 2025. Fazel S, Geddes JR, Kushel M. The health of homeless people in high-income countries: descriptive epidemiology, health consequences, and clinical and policy recommendations. Lancet. 2014;384(9953):1529–40. Reilly J, Ho I, Williamson A. A systematic review of the effect of stigma on the health of people experiencing homelessness. Health Soc Care Commun. 2022;30(6):2128–41. Becker JN, Foli KJ. Health-seeking behaviours in the homeless population: a concept analysis. Health Soc Care Commun. 2022;30(2):e278–86. Ingram C, Buggy C, MacNamara I, Perrotta C. Just a knife wound this week, nothing too painful: An ethnographic exploration of how primary care patients experiencing homelessness view their own health and healthcare. PLoS ONE. 2024;19(7):e0299761. Kopanitsa V, McWilliams S, Leung R, Schischa B, Sarela S, Perelmuter S, et al. A systematic scoping review of primary health care service outreach for homeless populations. Fam Pract. 2023;40(1):138–51. Miler JA, Carver H, Masterton W, Parkes T, Maden M, Jones L, et al. What treatment and services are effective for people who are homeless and use drugs? A systematic ‘review of reviews’. PLoS ONE. 2021;16(7):e0254729. National Institute for Health and Social Care Excellence. Integrated health and social care for people experiencing homelessness [A-B] Evidence reviews for effectiveness of approaches to improve access to and engagement with health and social care and joined up approaches. London: (NICE); 2022. National Institute for Health and Social Care Excellence. Integrated health and social care for people experiencing homelessness [C] Evidence review for views and experiences of health and social care for people experiencing homelessness. London: NICE; 2022. National Institute for Health and Social Care Excellence. NICE guideline NG214. Integrated health and social care for people experiencing homelessness. London: National Institute for Health and Social Care Excellence; 2022. Dorney-Smith S. Report of nurse outreach to rough sleeping clients residing in the City of London. Sept 2020 – June 2021. Doctors of the World; 2021. Dorney-Smith S. Delivering outreach primary health care to rough sleepers in the City of London. In: Institute, DoHSCaTQsN, editors. Homeless and Inclusion Health Nursing Case Studies: Raising awareness and understanding of Homeless and Inclusion Health Nursing and demonstrating the value of this specialist role. The Queen’s Nursing Institute; 2022. pp. 25–9. Dorney-Smith S, Sivasathiaseelan D. Report of a 6-month pilot of medical and nurse outreach to rough sleeping clients residing in the City of London: December 2019 – June 2020. Doctors of the World UK.; 2020. Skivington K, Matthews L, Simpson SA, Craig P, Baird J, Blazeby JM, et al. A new framework for developing and evaluating complex interventions: update of Medical Research Council guidance. BMJ. 2021;374:n2061. Šimon M, Latečková B, Potluka O. Health and healthcare use of homeless population: Evaluation study of joint social work and healthcare provision. Int J Nurs Stud. 2025;161:104929. Ungpakorn R, Rae B. Health-related street outreach: Exploring the perceptions of homeless people with experience of sleeping rough. J Adv Nurs. 2020;76(1):253–63. Bell L, Whelan M, Fernandez E, Lycett D. Nurse-led mental and physical healthcare for the homeless community: A qualitative evaluation. Health Soc Care Commun. 2022;30(6):2282–91. McCrabb S, Mooney K, Elton B, Grady A, Yoong SL, Wolfenden L. How to optimise public health interventions: a scoping review of guidance from optimisation process frameworks. BMC Public Health. 2020;20(1):1849. Kennedy CJ, Grewal J, Warren G, Schmidt J, Biagioni JB, Garcia-Barrera MA. Brain injury, mental health and substance use in homeless populations: community-generated recommendations for healthcare service delivery and research. BMC Health Serv Res. 2025;25(1):715. Collins LM, Murphy SA, Nair VN, Strecher VJ. A strategy for optimizing and evaluating behavioral interventions. Ann Behav Med. 2005;30(1):65–73. Landoll RR, Vargas SE, Samardzic KB, Clark MF, Guastaferro K. The preparation phase in the multiphase optimization strategy (MOST): a systematic review and introduction of a reporting checklist. Translational Behav Med. 2022;12(2):291–303. Braun V, Clarke V. Thematic analysis: A practical guide. 2021. Hoffmann TC, Glasziou PP, Boutron I, Milne R, Perera R, Moher D, et al. Better reporting of interventions: template for intervention description and replication (TIDieR) checklist and guide. BMJ: Br Med J. 2014;348:g1687. Pratt B. What are Important Ways of Sharing Power in Health Research Priority Setting? Perspectives From People With Lived Experience and Members of the Public. J Empir Res Hum Res Ethics. 2021;16(3):200–11. Stubbs JL, Thornton AE, Sevick JM, Silverberg ND, Barr AM, Honer WG, et al. Traumatic brain injury in homeless and marginally housed individuals: a systematic review and meta-analysis. Lancet Public Health. 2020;5(1):e19–32. Crane M, Joly L, Daly BJ, Daly B, Gage H, Manthorpe J, et al. Integration, effectiveness and costs of different models of primary health care provision for people who are homeless: an evaluation study. Health social care delivery Res. 2023;11(16):1–217. Crane M, Joly L, Daly BJ, Gage H, Manthorpe J, Cetrano G, et al. Primary health care for people experiencing homelessness: the effectiveness of specialist and mainstream health service provision. Br J Gen Pract. 2024;74(749):568. Padgett DK. Homelessness, housing instability and mental health: making the connections. BJPsych Bull. 2020;44(5):197–201. Department of Health and Social Care. 10 Year Health Plan for England: Fit for the future. London: Department of Health and Social Care; 2025. Hurst G, Teizeira L, Davies N. A smarter apporach to homelessness: prioritising prevntion in the 2025 spending review. London: Centre for Homlessness Impact; 2025. Queen’s Nursing Institute. Homeless inclusion nurses - Practitioners addressing inequalities in health. London: Department of Health & Social Care; 2022. Collins LM, Murphy SA, Strecher V. The multiphase optimization strategy (MOST) and the sequential multiple assignment randomized trial (SMART): new methods for more potent eHealth interventions. Am J Prev Med. 2007;32(5 Suppl):S112–8. O’ Cathain A, Croot L, Duncan E, Rousseau N, Sworn K, Turner KM, et al. Guidance on how to develop complex interventions to improve health and healthcare. BMJ Open. 2019;9(8):e029954. Pérez D, Van der Stuyft P, Zabala MC, Castro M, Lefèvre P. A modified theoretical framework to assess implementation fidelity of adaptive public health interventions. Implement Sci. 2016;11(1):91. Zainal NH, Liu X, Leong U, Yan X, Chakraborty B. Bridging Innovation and Equity: Advancing Public Health Through Just-in-Time Adaptive Interventions. Annu Rev Public Health. 2025;46. Additional Declarations Competing interest reported. Sam Dorney-Smith was commissioned by the Centre for Homelessness Impact as an Independent Advisor to the Test and Learn Programme. She supported the delivery of stakeholder workshops. She was funded through Inclusion Nursing to deliver the training component of the intervention. Funding was not contingent on the content or implementation strategy of the training components, which were partly developed and refined through the optimisation workshops. Supplementary Files SupplementA.SystemStakeholderTopicGuide.docx Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 27 Mar, 2026 Reviewers agreed at journal 23 Mar, 2026 Reviewers invited by journal 18 Mar, 2026 Editor assigned by journal 16 Mar, 2026 Editor invited by journal 24 Feb, 2026 Submission checks completed at journal 24 Feb, 2026 First submitted to journal 24 Feb, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8855118","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":608480931,"identity":"354f8371-5cb1-4f80-a10c-eb1363c224b7","order_by":0,"name":"Rhiannon Evans","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA9ElEQVRIiWNgGAWjYBAC+wYgwfjnnxw/iMdjAKEZGA7g1mIAIhjbDhhLNoC1QGiitCRuACniYSBGi0Tys4c/gbYYHz/87MObAgMJBvbDD5h5zuDxi0SauTHvnz9yZmfSjGfOMQBq4UkzYOa5gccWngNm0owfDhib3WAwZuYx+FPHwJDDwMzzAZ+W498kf844kLh5BvtnoBagLfxvCGhh7zGT4O0Bel+CxxiiRQJkCz6HsfeUSfMCvS9xJqeYEeQXNolnBgfn4PN+M/s2yZ9twKhsP76Z4c0fAwl+/uSHD94cw60FE7Ax4I2VUTAKRsEoGAXEAAALzU7Xb3y4HgAAAABJRU5ErkJggg==","orcid":"","institution":"Cardiff University","correspondingAuthor":true,"prefix":"","firstName":"Rhiannon","middleName":"","lastName":"Evans","suffix":""},{"id":608480937,"identity":"307fc40d-8798-47ed-ad47-7aa2178732c5","order_by":1,"name":"Peter Mackie","email":"","orcid":"","institution":"Cardiff University","correspondingAuthor":false,"prefix":"","firstName":"Peter","middleName":"","lastName":"Mackie","suffix":""},{"id":608480939,"identity":"14671ef4-4089-46dd-ba44-8b614821d691","order_by":2,"name":"Linda Adara","email":"","orcid":"","institution":"Cardiff University","correspondingAuthor":false,"prefix":"","firstName":"Linda","middleName":"","lastName":"Adara","suffix":""},{"id":608480943,"identity":"7e5c5cc8-6df4-461e-9a8a-eb8170a16b3b","order_by":3,"name":"Yvonne Moriarty","email":"","orcid":"","institution":"Cardiff University","correspondingAuthor":false,"prefix":"","firstName":"Yvonne","middleName":"","lastName":"Moriarty","suffix":""},{"id":608480944,"identity":"8f9a8218-f754-45d0-887f-7739bf3ffec0","order_by":4,"name":"Rachel Brown","email":"","orcid":"","institution":"Cardiff University","correspondingAuthor":false,"prefix":"","firstName":"Rachel","middleName":"","lastName":"Brown","suffix":""},{"id":608480945,"identity":"0a1291fa-7545-40e3-ba8e-e9f1c3412a4a","order_by":5,"name":"Samantha Dorney-Smith","email":"","orcid":"","institution":"University College London","correspondingAuthor":false,"prefix":"","firstName":"Samantha","middleName":"","lastName":"Dorney-Smith","suffix":""},{"id":608480947,"identity":"01e67282-bf7e-4d40-90f4-84e9e408be79","order_by":6,"name":"James White","email":"","orcid":"","institution":"Cardiff University","correspondingAuthor":false,"prefix":"","firstName":"James","middleName":"","lastName":"White","suffix":""}],"badges":[],"createdAt":"2026-02-11 19:23:13","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8855118/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8855118/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105076631,"identity":"f3e1ee16-362a-4074-967c-4ac4fd0a6a19","added_by":"auto","created_at":"2026-03-20 16:25:39","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":108315,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eLogic model describing programme theory of outreach with a health specialism\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8855118/v1/4a902180f4d94b9374c0a18b.png"},{"id":105562992,"identity":"f3629d93-bbf0-4932-9f28-467cbd77ecd0","added_by":"auto","created_at":"2026-03-27 12:45:33","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2676867,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8855118/v1/aeb7cdbe-3b97-46bc-81f8-394015ecb69f.pdf"},{"id":105076632,"identity":"ac2ca1d1-89a0-4957-8570-8ae313fb7145","added_by":"auto","created_at":"2026-03-20 16:25:39","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":42181,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementA.SystemStakeholderTopicGuide.docx","url":"https://assets-eu.researchsquare.com/files/rs-8855118/v1/29d7c25219f3296ea0e9169e.docx"}],"financialInterests":"Competing interest reported. Sam Dorney-Smith was commissioned by the Centre for Homelessness Impact as an Independent Advisor to the Test and Learn Programme. She supported the delivery of stakeholder workshops. She was funded through Inclusion Nursing to deliver the training component of the intervention. Funding was not contingent on the content or implementation strategy of the training components, which were partly developed and refined through the optimisation workshops.","formattedTitle":"Outreach services with a health specialism for people rough sleeping in the UK: An intervention optimisation study","fulltext":[{"header":"BACKGROUND","content":"\u003cp\u003ePeople experiencing homelessness report poorer health outcomes than those who are housed (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e), and have a risk of all-cause mortality that is around twice that found in the general population (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). This excess mortality is in part explained by higher exposure to alcohol, smoking, drug use, and mental disorders (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). Engagement with appropriate healthcare can be challenging due to perceived and enacted stigma from health professionals, a lack of timely provision, and complex administrative processes (\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). Precarity in meeting physiological needs, such as housing, food and clothing, can mean that health is not prioritised (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe evidence-base for interventions that promote healthcare engagement is mixed, with a lack of approaches that effectively remove barriers to service uptake, including access to appropriate accommodation (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). However, syntheses conducted by the National Institute for Health and Social Care Excellence (NICE) have identified the potential of integrated outreach services (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). As a result, associated guidelines recommend the use of multi-disciplinary teams to deliver mobile outreach provision to individuals who may not otherwise have access to, or engage with, existing health and social care provision (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn 2023, the Centre for Homelessness Impact (CHI), commissioned by the UK Government\u0026rsquo;s Ministry of Housing, Communities and Local Government (the Department for Levelling Up, Housing and Communities at the time of funding), launched a programme of research to generate an evidence-base for service delivery. As part of this programme, it funded an evaluation of a specific model of outreach service for people experiencing homelessness, namely outreach with a health specialism. For the purpose of the study, outreach nurses were newly commissioned to deliver the health specialism, with Change Grow Live (CGL) (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.changegrowlive.org/\u003c/span\u003e\u003cspan address=\"https://www.changegrowlive.org/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e) serving at the intervention provider.\u003c/p\u003e\n\u003ch3\u003eOutreach with a Health Specialism\u003c/h3\u003e\n\u003cp\u003eOutreach with a health specialism aims to remove barriers to healthcare engagement by having health professionals deliver services directly to people in their own environment. For those who experience rough sleeping, this may be in a variety of locations, including on the street. The model is in routine practice across some areas of the UK, though reach can be variable and provision is often tailored to meet the needs of the local context. For the purpose of the current study, the intervention is based on a version of the model that has been delivered in central London (\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDespite best practice methodological guidance recommending that interventions have a clearly articulated programme theory describing the underpinning causal mechanisms (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e), the theoretical basis of this approach is generally underspecified. Components tend to be more explicitly described, with the intervention delivering a wide range of potential activities. These include, but are not limited to, professionals providing health checks, offering health advice and screening, and offering vaccinations and some urgently necessary medications. Delivery agents commonly include nurses, dentists, General Practitioners (GPs) and pharmacists (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eWhile evaluations have been characterised by a lack of randomised study designs, there is some indication that outreach with a health specialism can increase uptake in vaccinations, screening and dental treatment, along with a reduction in emergency hospital visits and admissions (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). However, without a clear understanding of the mechanisms through which this type of intervention brings about change, the range of outcomes that can be plausibly targeted is not fully evident. This includes whether health outreach can improve access to appropriate accommodation and housing stability.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eIntervention Modelling and Optimisation\u003c/h2\u003e \u003cp\u003eIn the current study we present the conceptual modelling of the outreach with a health specialism intervention evaluated as part of the CHI commission. We developed a programme theory describing: the components to be delivered; the implementation processes that ensures delivery; the causal mechanisms that components should potentiate; and the outcomes that should be impacted.\u003c/p\u003e \u003cp\u003eImportant to any generation of programme theory is an understanding of the intervention\u0026rsquo;s delivery context, and how features of the system will interact with causal mechanisms, working to support or inhibit the pathway to targeted outcomes (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). To date there is only a small body of qualitative evidence from the UK exploring how the health, social care and housing system might influence the functioning of health outreach (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e). The vast majority of research has been conducted in the USA and Australia (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). There is limited systematic consideration of whether reported context-intervention are also characteristic of the UK. As such, there is a need to describe how the intervention might operate in the UK and explore any system specificities.\u003c/p\u003e \u003cp\u003eThrough the process of describing the programme theory, there is a possibility of identifying limitations with the intervention. This includes incompatibility between components, weaknesses in proposed causal pathways, contextual characteristics that will inhibit delivery, or outcomes that are not theoretically justified. In response, it may be necessary to optimise intervention components, implementation processes, and delivery context.\u003c/p\u003e \u003cp\u003eOptimisation is a concept used across evaluation research and implementation science, broadly describing a data-driven process for improving interventions (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). It is increasingly recognised as a much needed phase of evaluation in homelessness research (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). In accordance with Medical Research Council guidance on the development and evaluation of interventions (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e), we conceive optimisation as the process of refinement. It is done with the intention of enhancing intervention functioning, ensuring it is optimally designed to be feasible, acceptable and activate intended causal mechanisms.\u003c/p\u003e \u003cp\u003eWe differentiate this approach from optimisation evaluation research designs, as prescribed by the MOST guidance (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). These generally entail the randomised experiments of components to identify which ones best meet the optimisation criteria (e.g. most cost-effective). To note, our approach does have some alignment with the initial preparation phase of MOST, which takes a mixed method approach to identifying and piloting theoretically and empirically justified intervention components (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). However, where MOST progresses to a fractional-factorial Randomised Controlled Trial to compare intervention components, our optimisation process will be followed by a pilot cluster Randomised Controlled Trial.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eResearch Questions\u003c/h3\u003e\n\u003cp\u003eIn this paper we describe the process of developing the programme theory and optimising the intervention. Specifically, we address the following research questions:\u003c/p\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eWhat are the intervention\u0026rsquo;s mechanisms, components and implementation processes, outcomes and relevant aspects of context?\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eHow can intervention components, implementation processes and context be optimised to enhance intervention functioning?\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eHow can the optimised intervention be operationally delivered?\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e"},{"header":"METHODOLOGY","content":"\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eDesign\u003c/h2\u003e \u003cp\u003eThe optimisation phase comprised three stages of research: 1) rapid evidence review of intervention manual and training materials from the London model (\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e), along with the research evidence-base, to construct a candidate programme theory; 2) stakeholder and lived experience workshops and interviews to consider the accuracy of the candidate programme theory, address gaps in understanding, and identify necessary refinements to optimise intervention functioning; and 3) stakeholder workshop to confirm final programme theory, agree refinements and develop a delivery plan to operationalise refinements. All research was designed and conducted by the commissioned research team at Cardiff University. The team worked in consultation with Sam Dorney-Smith, an independent inclusion health nurse consultant with experience of designing and delivering an outreach intervention model. She was commissioned by Centre for Homelessness Impact (CHI) to provide the training component to nurses and support optimisation from a practice perspective.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eStudy Setting and Recruitment\u003c/h3\u003e\n\u003cp\u003eThe study was conducted in England. We purposively sampled three groups of national stakeholders to guide intervention description and refinement.\u003c/p\u003e \u003cp\u003eTwelve professionals with experience of developing, delivering and/or funding outreach with a health specialism in the UK were sampled to participate in two professional stakeholder workshops. These professionals were identified by the intervention training provider (SDS), the intervention provider CGL, the funder CHI, and the research commissioner the Ministry of Housing, Communities and Local Government.\u003c/p\u003e \u003cp\u003eSeven experts with lived experience were recruited to participate in one stakeholder workshop. These experts were members of the CHI Lived Experience Network.\u003c/p\u003e \u003cp\u003eTwenty-three professional system stakeholders were purposively sampled to participate in semi-structured interviews, with a total of eight taking part. These were identified by individuals participating in the professional stakeholder workshops. They included professionals working in the statutory and voluntary sector, along with researchers with experience of working with homeless populations to understand service needs and experiences.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eData Collection\u003c/h2\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003eRapid evidence review\u003c/h2\u003e \u003cp\u003eWe reviewed the intervention manual, training materials and evidence-base to construct a candidate programme theory describing the following domains: mechanisms summarising how the intervention is intended to bring about change; components; implementation processes; targeted and potential unintended outcomes; and features of the context that will likely interact with mechanisms to modify intervention functioning. Grey literature specific to the intervention was identified through consultation with the intervention training provider (SDS) and the intervention provider CGL. We conducted a search of four bibliographic databases to identify prior models and evaluations of homelessness outreach delivered by health professionals: Scopus, CINAHL, PsycInfo, and MEDLINE. Search terms broadly mapped onto the population and intervention terms of PICO (Population, Intervention, Comparator, Outcome): \u0026lsquo;Homeless*\u0026rsquo; AND \u0026lsquo;Nurse*\u0026rsquo; AND \u0026lsquo;Outreach\u0026rsquo;. Searches were conducted in June 2024 and updated in March 2025.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e\n\u003ch3\u003eProfessional stakeholder workshops\u003c/h3\u003e\n\u003cp\u003eWe conducted one online workshop with all twelve professional stakeholders in June 2024 and a second workshop with seven of these stakeholders in November 2024. Both workshops were hosted on Microsoft Teams and facilitated by two members of the research team. The first workshop comprised a presentation on the candidate programme theory and was followed by a guided discussion of each domain, exploring the accuracy of our assumptions, addressing knowledge gaps, and identifying potential refinements. The second workshop included a presentation and discussion on the revised programme theory to reach agreement on its validity, confirm recommended refinements and agree a plan to operationalise them. Summary notes were taken of each workshop.\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eLived experienced stakeholder workshop\u003c/h2\u003e \u003cp\u003eWe conducted an online workshop with people with lived experience of homelessness in November 2024. The workshop was hosted through Microsoft Teams and facilitated by two researchers, with support from a member of CHI staff. Discussion had a particular focus on exploring the context domain of programme theory (e.g. perceived contextual inhibitors of participation) and refinements to optimise intervention recruitment and acceptability. Summary notes were taken of the workshop.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eSystem stakeholder interviews\u003c/h2\u003e \u003cp\u003eWe undertook semi-structured interviews with system stakeholders between November 2024 and January 2025. Interviews were conducted by a member of the research team via telephone or Microsoft Teams. They adhered to a pre-specified topic guide, with questions exploring understanding and experiences of the domains of programme theory (e.g. experience of proposed intervention components) and eliciting recommendations for refinements (Supplement A). Interviews were audio recorded in the relevant software platform, transcribed and redacted where appropriate, before being checked for accuracy.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eData Analysis\u003c/h2\u003e \u003cdiv id=\"Sec14\" class=\"Section3\"\u003e \u003ch2\u003eCandidate programme theory\u003c/h2\u003e \u003cp\u003eWe extracted information from study reports identified from our rapid evidence review according to the a priori specified programme theory domains. The extant academic evidence-base had limited use, as descriptions of outreach models tended to lack a theoretical basis. Equally, a paucity of UK evidence meant a lack of insight into the localised contextual factors that might influence intervention functioning. In contrast, the grey literature was specific and sensitive to the review needs. As such we initially focused on extracting from the grey literature, drawing on wider research to verify our assumptions and address gaps in our theory. Where there were continued gaps in knowledge, we consulted with the intervention training provider (SDS), who was lead author on a large portion of the identified grey literature (\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). This was notably helpful in unpacking some of the underpinning causal mechanisms that may drive intervention outcomes. From here we generated a slide deck to guide consultation, a narrative summary of the programme theory and an accompanying logic model.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eRefinement of programme theory\u003c/h2\u003e \u003cp\u003eSummary notes from the first professional stakeholder and lived experience stakeholder groups were analysed through content analysis, with codes derived from the programme theory domains. Coding was conducted by one researcher and then confirmed with the wider research team (RE, PM).\u003c/p\u003e \u003cp\u003eWe used thematic analysis to analyse system stakeholder data (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e), with a priori parent codes mapping onto the domains of programme theory (e.g. interventions components) and child and grandchild codes theorising specific aspects of the domain. Recommendations for modifications were included as child/grandchild codes within each domain. Themes were generated based on the coding framework, with themes being tested through consideration of negative cases (e.g. examining the strength of support for specific recommendations across data sources, and if there was potential for harm). Coding was conducted by one member of the research team and checked by a second (RE, JW).\u003c/p\u003e \u003cp\u003eWe integrated findings from the two stakeholder workshops and system stakeholder interviews to generate a narrative summary of new knowledge for the programme theory, along with recommendations for refinements. While there were variations in the foci of data from each data source, they were largely consistent. We also developed a slide deck of key findings to support the final professional stakeholder consultation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eFinal programme theory and operational plan for delivery\u003c/h2\u003e \u003cp\u003eWe undertook content analysis of the summary notes from the second workshop. Discussion points were integrated into the initial narrative description of the programme theory and associated logic model to generate a final programme theory. We also reported the final intervention using the Template for Intervention Description and Replication (TIDieR) checklist (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e). For the recommendations, we constructed a slide deck summarising the recommendations and potential operational delivery plan. We subsequently hosted a meeting with CGL to share the operational plan (e.g. what needed to be included in their nurse training sessions) so they could take forward the necessary refinements.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eEthical Considerations\u003c/h2\u003e \u003cp\u003e \u003cstrong\u003eEthical approval\u003c/strong\u003e \u003cp\u003e was provided by Cardiff University School of Medicine Research Ethics Committee (REF: 24/38). To protect the anonymity and confidentiality of participants in the study, we have not provided detailed information on socio-demographic or professional characteristics.\u003c/p\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eRigour and Reflexivity\u003c/h2\u003e \u003cp\u003eWe achieved methodological rigour through a number of strategies. While sampling relied on a purposive approach, we recruited a range of stakeholders and participants, including those who identified as having more negative views of the outreach model. This was to ensure diverse data and the potential for negative cases. Consultations and interviews were audio-recorded, with the latter being transcribed and quality checked by a member of the research team. This ensured accuracy in representing data. Analysis of summary notes and interview data involved multiple members of the research team, ensuring credibility in interpretations. Having a clear research aim and design (e.g. intervention optimisation) that translated into a specified analytical framework (e.g. generating codes and themes linked to programme theory domains), offered a clear structure and transparent process.\u003c/p\u003e \u003cp\u003eWe maintained a highly sensitive approach to reflexivity throughout the study, reflecting on our positionality and power in relation to an underserved population. The research team met weekly to discuss and challenge interpretations and assumptions about the intervention. The research team regularly met with the intervention training provider (SDS) to ensure that data collection and analysis were grounded in the needs of practitioners, while responding to their real-world constraints. Throughout the process we adhered to recommended best practice in power sharing in health research (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e). For example, in the lived experience stakeholder group consultation, we had clear definitions of roles and influence, inclusive facilitation, and stakeholder control over the nature and extent of engagement.\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003eWe present the results according to the three sequential phases of activity undertaken as part of the optimisation process: 1) development of candidate programme theory; 2) refinement of programme theory; and 3) confirmation of final programme theory and development of operational delivery plan.\u003c/p\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003eCandidate Programme Theory\u003c/h2\u003e \u003cp\u003eOur rapid review identified a total of 108 unique reports, comprising both grey literature and published research. We developed the candidate programme theory from these reports.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eMechanisms\u003c/strong\u003e \u003cp\u003eWe identified six central mechanisms through which the intervention should bring about change. Description of these mechanisms is presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The extant academic literature provided limited theorisation of underpinning causal pathways, so mechanisms were largely generated through consultation with the intervention training provider (SDS). Mechanisms focused on the potential novelty of engagement with a nurse, and how it might open an opportunity for new conversations about health, social care and housing support. They extended to address professional identity, and how being a nurse could increase service users\u0026rsquo; confidence in health care provision. There was also a focus on nurses\u0026rsquo; knowledge and skills, and their unique capability to secure appropriate healthcare, which may motivate service users to engage. Nurse\u0026rsquo;s skills also included clinical and legal advocacy, and how they may be able to secure health, social care and housing provision based on their clinical and legal knowledge.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eTable 1. Causal mechanisms of outreach with a health specialism intervention\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"964\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 20.5607%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMechanism\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79.4393%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDescription of Mechanism\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 20.5607%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026lsquo;Fresh\u0026rsquo; engagement\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79.4393%;\"\u003e\n \u003cp\u003eNurses can introduce a \u0026lsquo;fresh\u0026rsquo; engagement for people experiencing homelessness, which may increase the likeliness of taking part in a discussion about their needs. While this \u0026lsquo;fresh\u0026rsquo; engagement focuses on health, it can open opportunities to have new and reframed conversations around housing and other social care needs, which might lead to engagement with housing services.\u003csup\u003ea\u003c/sup\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 20.5607%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOutreach nurses\u0026rsquo; trusted professional identity\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79.4393%;\"\u003e\n \u003cp\u003ePeople experiencing homelessness may recognise the professional identity of nurses and trust their knowledge and advice. Service users may also recognise nurses\u0026rsquo; professional responsibility around confidentiality, safeguarding and compliance, making them more willing to share their needs.\u003csup\u003ea\u003c/sup\u003e\u0026nbsp; Reliant on nurses ability to organically build positive, trusting relationships through empathetic communication, compassion and trauma-informed approach.\u003csup\u003ebcd\u003c/sup\u003e People\u0026rsquo;s positive experience of a trustworthy and reliable health professional may increase engagement with other outreach services related to housing and potentially increase offers of appropriate accomodation.\u003csup\u003ea\u003c/sup\u003e \u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 20.5607%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eClinical and legal advocacy\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79.4393%;\"\u003e\n \u003cp\u003eNurses should possess clinical and legal knowledge. They should use this knowledge to advocate for the service user\u0026rsquo;s health, social care and housing needs.\u003csup\u003ea\u003c/sup\u003e As nurses undertake outreach in the places where people live, they will likely have a more holistic understanding of service users\u0026rsquo; complex health needs than many other professionals, making them more effective at advocacy.\u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 20.5607%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eIdentifying health care needs as an accommodation entitlement\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79.4393%;\"\u003e\n \u003cp\u003ePeople who experience homelessness may not be owed a housing duty (e.g. people with No Recourse to Public Funds). However, having significant health care or support needs (e.g. self-neglect or serious brain injury), can activate a pathway to accommodation entitlement under the Care Act 2014. Nurses\u0026rsquo; assessment of a significant health need can open up eligibility for accommodation\u003csup\u003eb\u0026nbsp;\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 20.5607%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAppropriate service referral and engagement\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79.4393%;\"\u003e\n \u003cp\u003eThe clinical expertise of outreach nurses should ensure that service users are provided with accurate health assessments and referred to the health services that best meet their health needs. This might increase service users\u0026rsquo; confidence in, and uptake of, health, social care and housing services. Nurses may also help to offer practical support to facilitate service access (e.g. arranging appointments, offering reassurance and preparing individuals for service engagement), which can further bolster confidence and engagement in the system.\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 20.5607%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eInter-professional recognition and relationships\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79.4393%;\"\u003e\n \u003cp\u003eNurses will likely have a shared expertise, language and ways of working with other health professionals, which may increase system responsiveness to their advocacy.\u003csup\u003ea\u0026nbsp;\u003c/sup\u003eThe fact that they are \u0026lsquo;speaking the right language\u0026rsquo;, means that other professionals will be more likely to recognise and act upon the identified need.\u003csup\u003ebd\u003c/sup\u003e. Nurses will likely have existing working relationships with other health professionals and can draw upon these relationships to support multi-agency collaboration.\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eThe table reports the causal mechanisms underpinning the outreach with a health specialism intervention. The description of the mechanisms reports the source of the description: \u003csup\u003ea\u0026nbsp;\u003c/sup\u003eRapid evidence review, \u003csup\u003eb\u0026nbsp;\u003c/sup\u003eProfessional stakeholder workshop, \u003csup\u003ec\u0026nbsp;\u003c/sup\u003eLived experience workshop, \u003csup\u003ed\u003c/sup\u003e System stakeholder interviews.\u003c/p\u003e \u003cp\u003eWe generated an important mechanistic pathway to help explain one of the ways in which health and housing may be inter-related. Here we identified that people may have more immediate housing entitlements if they are identified to have a significant healthcare needs. Nurses\u0026rsquo; engagement with service users\u0026rsquo; might also increase the opportunity for Care Act 2014 assessments and Mental Health assessments, hence activating the pathway to accommodation entitlement.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eTarget population\u003c/strong\u003e \u003cp\u003eFor the purposes of this study, the funder pre-specified that the intervention should target individuals who are \u0026lsquo;living\u0026rsquo; on the streets (defined as those seen sleeping on the streets on at least 6 separate occasions over a period of up to 6 months). The reason for this inclusion criteria was twofold. First, it is likely that people living on the streets will be better known to outreach services, therefore significantly increasing the likelihood of successful baseline and follow up data collection. Second, this subgroup of people rough sleeping is further away from being accommodated than peers who spend less time sleeping on the streets, and therefore the intervention has potential for greatest impact. Crucially for the pilot Randomised Controlled Trial, nurses will be permitted to support other people rough sleeping, but trial eligibility criteria will focus only on those \u0026lsquo;living\u0026rsquo; on the streets.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eComponents and implementation process\u003c/b\u003e: We described four intervention components to be delivered as part of the intervention. Description of the components, and their associated implementation process, is presented in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. These components were largely identified from the London model of outreach (\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e), while the activities to be undertaken as part of each component (e.g. services administered during outreach sessions) were derived from the wider evidence-base. Specified components were: training of outreach nurses to ensure knowledge and skill sufficiency; outreach shifts to engage with service users, meet immediate health needs, and motivate future service uptake; clinical supervision of nurses by a lead nurse to monitor wellbeing and quality assurance; and nurse support for service follow-up to ensure continued health, social care and housing uptake, often through participation in Multi-Disciplinary Teams (MDTs).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComponents and implementation of outreach with a health specialism intervention\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComponent\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCandidate programme theory\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRefinements for final programme theory\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eStakeholder recommendations and operational delivery plan\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIntervention principles\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFlexible and tailored approach.\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEnsure explicit description of intervention as: flexible, responsive and person-centred\u003csup\u003ebcd\u003c/sup\u003e; generalist\u003csup\u003eb;\u003c/sup\u003e and adopting a broad definition of rough sleeping.\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSee \u003cb\u003eKey principles, skills and knowledge in outreach nurse training\u003c/b\u003e and \u003cb\u003eTailoring outreach to service users.\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOutreach nurse training\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTraining will include a combination of standard and bespoke training.\u003c/p\u003e \u003cp\u003e\u003cb\u003eStandard Training\u003c/b\u003e: Standardised training modules will be made available to nurses through CGL. Training providers will include QNI, LNNM, Fairhealth and Aneemo.\u003c/p\u003e \u003cp\u003e\u003cb\u003eBespoke Training\u003c/b\u003e: Nurses will receive a bespoke training package. Four half day training sessions will be delivered by the training provider (SDS). Two will be delivered online and two will be delivered in person. These will be complemented by a range of other electronic resources. \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNeed to include lived experience voices.\u003csup\u003ec\u003c/sup\u003e Knowledge and skill set should extend to include: (radical) safeguarding, mental health as a chronic disease (e.g. hoarding), management of common clinical conditions with discussions on clinical risk, communication strategies, reflective practice, cultural competence, and key legislation (e.g. housing law and the Care Act 2014).\u003csup\u003ebcd\u003c/sup\u003e Ensure nurses are trained in inclusive language.\u003csup\u003ec\u003c/sup\u003e Appoint nurses with requisite clinical and non-clinical skills.\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eLived experience voices in outreach nurse training\u003c/b\u003e: Bespoke training modules to include training with individuals who have lived experience. This will focus on role-playing, so nurses can build confidence to engage with and support those with complex needs and a mistrust of healthcare systems. The training provider to design training modules to include activities that support lived experience input.\u003c/p\u003e \u003cp\u003e\u003cb\u003eKey principles, skills and knowledge in outreach nurse training\u003c/b\u003e: Bespoke training modules to be aligned with key principles. Training provider to ensure core training modules are aligned with these principles and deliver skills. Where there is limited time to cover all additional skill sets, CGL to ensure nurses undertake training CGL to construct job descriptions and appoint outreach nurses with demonstrable clinical and non-clinical skill sets that will enable them to work in accordance with intervention principles.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOutreach shifts\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNurses to accompany outreach workers on shifts approximately two days per working week (15\u0026ndash;16 hours), offering direct support to service users.\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNeeds to be flexible in times, locations and seasons.\u003csup\u003ebcd\u003c/sup\u003e Focus on building sustained and trusting relationships.\u003csup\u003ec\u003c/sup\u003e Need reliable technology for accessing and recording information.\u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eTailoring outreach to service users\u003c/b\u003e: Nurses to be flexible in their approach. The training provider to ensure core training modules align with principles.\u003c/p\u003e \u003cp\u003e\u003cb\u003eEfficient data generation and flow\u003c/b\u003e: Nurses require appropriate and functioning equipment to undertake outreach. This includes technology to record service users\u0026rsquo; health and medical equipment to meet immediate health needs. CGL to check and ensure that nurses have all required provision.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOutreach nurse supervision\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLead nurse to provide nurses with weekly clinical supervision.\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLead nurse to encourage reflective practice, so nurses can manage emotions, prevent burnout, process experiences and refine their approaches.\u003csup\u003ec\u003c/sup\u003e Lead nurse to coordinate and support continued programme of development.\u003csup\u003ed\u003c/sup\u003e Lead nurse can support if nurse reaches roadblock in advocacy.\u003csup\u003ea\u003c/sup\u003e Can coordinate a peer-led community of practice.\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eTailoring outreach to service users\u003c/b\u003e: Nurses to be flexible in their approach. CGL to ensure supervision supports this tailored approach.\u003c/p\u003e \u003cp\u003e\u003cb\u003eSupportive supervision and community of practice\u003c/b\u003e: Supervision to have clear focus on supporting wellbeing of nurses to avoid burnout and monitor nurses use of reflective practice. CGL to construct job description and appoint lead nurse with skill set to support nurse wellbeing. CGL to support peer-led community of practice. Lead nurse to monitor nurses training needs.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eService follow-up and Multi-disciplinary Team (MDT) meetings\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNurses will need to follow-up with health, social care and housing services to ensure access to provision for the service users.\u0026nbsp;May have to liaise with, organise and attend relevant MDT meetings to advocate for service user.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNurses need time for data entry and service follow-up.\u003csup\u003eb\u003c/sup\u003e Nurses need to attend follow-up appointments with service users and not just signpost them on.\u003csup\u003ec\u003c/sup\u003e Service-follow-up will often involve investigative work to ensure information is correct and complete so that continuous care it appropriate to the service users\u0026rsquo;s needs.\u003csup\u003eb\u003c/sup\u003e Different areas will have different infrastructures and different multi-disciplinary teams. Need to make sure nurses are not duplicating efforts but adding value.\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eAttendance at service user appointment\u003c/b\u003e: Nurses should have ability and capacity to attend appointments with service users, as signposting to follow-on services is largely ineffective. Training provider to emphasise this core training modules and CGL to ensure supervision encourages this as resources allow.\u003c/p\u003e \u003cp\u003e\u003cb\u003eEfficient data generation and flow\u003c/b\u003e: Data storge and sharing within delivery organisation and with other institutions needs to be addressed. CGL to monitor data flow throughout pilot study, working to ensure efficiency and tackle issues.\u003c/p\u003e \u003cp\u003e\u003cb\u003eConfidence and capability in service-follow up\u003c/b\u003e: To support service-follow up nurses need to feel confident to build relationships with health and non-health care sectors. They will require the skills to achieve this. Intervention developer to support confidence and capability in service follow-up during core training modules. CGL to encourage this skill through supervision, reflective practice and peer-led community of practice, identifying additional training where relevant.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eThe table reports the components that comprise outreach with a health specialism intervention. The description of the components reports the source of the description: \u003csup\u003ea\u003c/sup\u003e Rapid evidence review, \u003csup\u003eb\u003c/sup\u003e Professional stakeholder workshop, \u003csup\u003ec\u003c/sup\u003e Lived experience workshop, \u003csup\u003ed\u003c/sup\u003e System stakeholder interviews.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eOutcomes\u003c/b\u003e: The funder pre-specified the primary outcome in the pilot Randomised Controlled Trial as the increased number of people moved off the street into appropriate accommodation. This is assessed by the CHI adapted version of the Residential Time-Line Follow-Back (RTLFB) survey. The secondary outcome is a health-related outcome, specified as Quality of Life and measured through the EQ-5D-5L. A range of additional outcomes were identified from the evidence-base for consideration in the present intervention model: number of health assessments; GP registrations and appointments; referrals to other services; service access and number of contacts; entry into specialised healthcare programmes such as detox; attendance at emergency departments; receipt of vaccinations and medications; and uptake of screening. Potential adverse, unintended outcomes were disengagement from a range of healthcare, social care and housing services.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eContext\u003c/strong\u003e \u003cp\u003eWe identified eight initial features of the health, social care, and housing system, that may inhibit intervention functioning. Description of these context factors are presented in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. They include the diverse needs and socio-demographic characteristics of service users, organisational capacity, and the inter-professional data infrastructure available for delivering holistic and integrated care.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eContext factors influencing functioning of outreach with a health specialism intervention\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eContext Factor\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDescription of Context Factor\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eComplex service user needs\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eService users may have complex multimorbid health profiles and needs. There may also be specific communication needs such as: literacy; learning difficulties; mental health problems; complex psychological trauma; acquired brain injury; limited capacity; neurodiversity; and addiction.\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLanguage and cultural competency\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eApproximately 20% of service users can require an interpreter for communication. It can be difficult to provide this on the streets due to background noise and it not being ideal to pass the phone between the service user and nurse.\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGeographical location of service users\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eService users may be located across a wide geographical area and nurses might spend a significant time travelling. Densely populated inner city areas may not be easily accessible by cars and alternative methods of transport are needed.\u003csup\u003ea\u003c/sup\u003e In rural areas, homelessness is more likely to be hidden and service users more difficult to locate.\u003csup\u003ed\u003c/sup\u003e. There may be boundary issues, and having a transient population that moves between areas can make it difficult to provide continuous care.\u003csup\u003ebc\u003c/sup\u003e It may be re-traumatising for service users to recount their histories, leading to disengagement.\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eProfile of service user population\u003c/b\u003e\u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eThe composition of the homeless population will vary by area. In some areas there may not be a large population of people who sleep rough, and so there may be a low rate of intervention eligibility. However, there may be a large portion of people who are based in hostels, and the intervention will not be able to meet their needs as they are ineligible for support.\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBelief systems and discourse around homelessness\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOutreach nurses, and the wider health, housing and social system, may hold belief systems that are not supportive of the intervention. For example, they may not agree with the principles of harm reduction or have negative or unhelpful attitudes towards people who sleep rough.\u003csup\u003eabcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOrganisational capacity\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eThere may be challenges in recruiting nurses with sufficient skill sets, especially in non-urban areas.\u003csup\u003eb\u003c/sup\u003e There may be a lack of capacity in outreach teams to accompany nurses during an outreach shift.\u003csup\u003eab,\u003c/sup\u003e Nurses will be required to undertake out-of-hours working, and they may not be outreach teams available to support this.\u003csup\u003eb\u003c/sup\u003e Nurses may experience burnout where this is limited organisational capacity to offer them support and supervision.\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eProfessional expertise and credibility\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNurses may not have the requisite baseline experience and expertise to navigate the health and housing system, and the intervention training may not be sufficient to ensure they are fully upskilled. They also might not have the requisite professional standing in the health, social care and housing system to advocate for change. This can be particularly challenging where nurses do not have an NHS registered account from which to email. Having a registered email account can help to emphasise shared working culture and practices between health professionals.\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSystem legal literacy and compliance\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eThere may be a lack of legal literacy and compliance within the health, social care and housing system to ensure a response to nurses\u0026rsquo; assessments. For example, local housing providers may not be aware that they there is a safeguarding assessment entitlement for someone who has been classified as experiencing \u0026lsquo;self-neglect\u0026rsquo;, and this could lead to alternative offers in terms of housing. Professionals (e.g. G.P. practices) may not share information with nurses due to perceived compliance with legal frameworks that state information cannot be shared without a signed consent form.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRecord generation maintenance and data sharing infrastructure\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePeople who experience homelessness can be a transient population, and there needs to be a centralised system for sharing data between areas.\u003csup\u003ec\u003c/sup\u003e There are issues with recording and sharing of information between professionals, as health, social care and housing providers may employ different recording systems, with different legal and security requirements.\u003csup\u003ea\u003c/sup\u003e Nurses may experience challenges in generating data records during outreach shifts if there is no consistent reporting template, a lack of secure back-up, poor signal and technological problems.\u003csup\u003eabd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAvailability of services in wider system\u003c/b\u003e\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOutreach provision will likely involve referral to other service providers. There may not be accessible and efficient referral routes, or the length of time that a referral takes may encourage disengagement.\u003csup\u003ec\u003c/sup\u003e The level of provision will vary by area, for example the availability of immediate care following a hospital discharge.\u003csup\u003eb\u003c/sup\u003e Some service users may not have the resources to attend services if the only available provision requires use of public transport.\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"2\"\u003eThe table reports the context factors that might influenced the functioning of the outreach with a health specialism intervention. The description of the context factors reports the source of the description: \u003csup\u003ea\u003c/sup\u003e Rapid evidence review, \u003csup\u003eb\u003c/sup\u003e Professional stakeholder workshop, \u003csup\u003ec\u003c/sup\u003e Lived experience workshop, \u003csup\u003ed\u003c/sup\u003e System stakeholder interviews.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003eRefinement of programme theory\u003c/h2\u003e \u003cp\u003eWe refined the programme theory and generated initial recommendations for optimisation through the professional and lived experience stakeholder consultations and system stakeholder interviews. Overall, participants confirmed our candidate programme theory, and there were no requirements to modify our description on the basis it was incorrect. Discussion and data focused on adding additional knowledge to deepen our understanding.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003eMechanisms\u003c/h2\u003e \u003cp\u003eAll participants agreed the relevance of the proposed mechanisms, although there was consideration that three key mechanisms would leverage more causal power when targeting outcomes. No new mechanisms were identified.\u003c/p\u003e \u003cp\u003eFirst, both stakeholder groups and system stakeholder interviews emphasised the importance of the mechanism related to professional identity, and service users\u0026rsquo; willingness to trust their knowledge and advice. However, stakeholders stated that this trust could not simply be obtained from a professional title, but was contingent on nurses\u0026rsquo; ability to build rapport, provide empathetic communication, and draw on a trauma-informed approach. Lived experience stakeholders emphasised the profound mistrust some individuals experiencing homelessness have of healthcare providers due to prior discriminatory treatment. They claimed that nurses would have to work to overcome this perception by affirming service users\u0026rsquo; dignity and value. This was also recognised by system stakeholders who cited the challenge of building trust:\u003c/p\u003e \u003cp\u003eIt's, it's difficult for us to build up that trust with someone anyway, isn't it?\u003c/p\u003e \u003cp\u003eBut someone that maybe has got a health focus that someone isn't quite ready to address, that or is scared or petrified of going into hospital would be a big challenge. So again, for us, we quite often we've got young people that are quite poorly but absolutely petrified of going to hospital. (System Stakeholder 8: Team leader, Homeless Shelter)\u003c/p\u003e \u003cp\u003eSecond, the professional stakeholder group and system stakeholders cited the importance of the advocacy mechanism, highlighting the need for nurses to advocate for service users\u0026rsquo; rights. One system stakeholder offered an extended account of how outreach made nurses better placed to advocate for a service user as they had a holistic and more realistic understanding of their health complexities and needs, as compared to hospital-based professionals:\u003c/p\u003e \u003cp\u003eSo for instance, if you look at a Mental Capacity and, and if you look at the Care Act, it's very prescriptive and someone can be in a hospital bed or wherever and, and things look great because you know the nurses are there and they\u0026rsquo;re (service user) active. You live in, you know, they've got a nice clean bed, and the food is brought to them and everything's looking, looking, OK, you know, ready for that discharge. But you go out to rough sleeping. All of those things and not, and just not achievable and that person cannot cope in that environment, so having, having eyes on the site and what's going on in real time at the location. Definitely informs how you then put that case forward and, and I don't know, bringing all the health-related things together. And presenting that in a way that explains that because the person themselves can't explain\u0026hellip; (System Stakeholder 5: Homeless Health and Clinical Lead)\u003c/p\u003e \u003cp\u003eThird, professional stakeholders and system stakeholders reported that interprofessional relationships were key to achieving the integrated and holistic approach to care that would be needed to effectively support service users. Professional stakeholders emphasised the importance of \u003cem\u003e\u0026lsquo;speaking the same language\u0026rsquo;.\u003c/em\u003e\u003c/p\u003e \u003cdiv id=\"Sec23\" class=\"Section3\"\u003e \u003ch2\u003eComponents and implementation process\u003c/h2\u003e \u003cp\u003eStakeholders from all sources agreed with the four intervention components and the proposed implementation process. No additional intervention components were identified as being needed to activate the causal mechanisms.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003ePrinciples\u003c/strong\u003e \u003cp\u003eA central feature of discussion across stakeholders was the principles needed to underpin the intervention. Participants emphasised the need for a flexible, inclusive, responsive, person-centred model, while balancing this with consistency to ensure equitable delivery across diverse areas and service users. There should be focus on responding to localised gaps in current outreach provision.\u003c/p\u003e \u003c/p\u003e \u003cp\u003eDiscussion extended to consider the target population. While there was agreement that individuals experiencing rough sleeping should be prioritised as they will likely have higher health needs, stakeholders felt the definition of rough sleeping needed to include those who are not visible on the streets. This includes those who live in tents, intermittently stay in hostels, or rely on other unstable living arrangements.\u003c/p\u003e \u003cp\u003eProfessional stakeholders also stated that healthcare provision should focus on generalist care that aligns with a primary care approach. To this end, nurses should be focused on initial assessment and services, with referral to specialist providers for further treatment. This reinforces the need for strong multi-sectoral collaborations.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eOutreach nurse training\u003c/strong\u003e \u003cp\u003eThis component was the focus of stakeholder discussion across sources. Lived experience stakeholders maintained that individuals with lived experience should be central to the design and delivery of training. This ensures nurses are exposed to real world scenarios and can foster deeper understanding and preparedness. Such an approach is particularly important for nurses with no prior experience of working with individuals experiencing homelessness.\u003c/p\u003e \u003c/p\u003e \u003cp\u003eThere was extensive comment on ensuring knowledge and skill development. Nurses should be trained in clinical and non-clinical skills related to: clinical risk management; unconscious bias; trauma-informed care; (radical) safeguarding; legal advocacy; supporting individuals with diverse needs (e.g. additional learning needs, autism and serious brain injuries), different age groups (e.g. young people), different gender identities, different cultural backgrounds, and different clinical conditions. Lived experience stakeholders observed a central barrier to service engagement is the use of complex, bureaucratic and condescending language, including terms such as \u0026lsquo;self-neglect\u0026rsquo; and \u0026lsquo;failed to attend\u0026rsquo;. To enact the mechanism around trust, stakeholders also emphasised the need to train nurses in empathetic approaches.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eOutreach with health specialism shifts\u003c/strong\u003e \u003cp\u003eAll stakeholder groups stressed the importance of outreach shifts being tailored to the needs of local populations, offering care at varied times, locations and seasons. As part of this flexible approach, they also indicated the need to use various transport methods (e.g. bicycles and vans) to enhance mobility, accessibility and reach. Lived experience stakeholders stated the need for accessible outreach locations, including community hubs such as soup kitchens or hostels, so that service users feel comfortable. Specifically related to the mechanism of professional identity, lived experience stakeholders highlighted the need for nurses to build a sustained and trusting relationships with service users over time. This is to be achieved through consistent and repeat contact where viable. System stakeholders were notable in highlighting implementation barriers that would need to be anticipated, including having technology that would reliably work and access information\u003c/p\u003e \u003c/p\u003e \u003cp\u003eThey (service users) might have set themselves up in an area that's difficult to find. So if people are using substances or if they have impaired memory then it can be challenging to get kind of an accurate history from people, and so a big challenge can be if you, if you're how much you can help somebody. If you can't see their health notes and records. And so the IT how, how you link in you know on it if you are out and about on the street. That's a big a big challenge as well. (System Stakeholder 4: Nurse Practitioner)\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eSupervision of outreach nurses\u003c/strong\u003e \u003cp\u003eLived experience stakeholders identified the need for supervision to encourage and support reflective practice, so that nurses are able to manage emotions, process experiences, prevent burnout and refine their approaches. System stakeholders also indicated the need for a continued development programme, which may be coordinated and supported by the lead nurse.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eService follow-up and MDT meetings\u003c/strong\u003e \u003cp\u003eAll stakeholders recognised the necessity of embedding nurses in MDTs to ensure services are addressing the interconnected needs of health, social care and housing. It was noted that nurses may need to build their confidence to undertake this role.\u003c/p\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec24\" class=\"Section2\"\u003e \u003ch2\u003eOutcomes\u003c/h2\u003e \u003cp\u003eThe pre-specified primary and secondary outcomes were identified as being appropriate by participants given the components and underpinning mechanisms. Additional outcomes identified in the evidence-base were confirmed and distilled to the most important (see Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003ePrimarily discussed within the professional stakeholder workshop and system stakeholder interviews, stakeholders cited the importance of an integrated approach that tackles both housing and health care due to their causal interconnectedness. Tackling health conditions may encourage housing stability, while appropriate accommodation will improve capacity to prioritise health. As one system stakeholder noted:\u003c/p\u003e \u003cp\u003eObviously the health and the housing and the benefits and everything is very linked up and it's got to be that holistic approach because that's why the people have ended up on the street because they've lost the links of all of those things and you can't do one without the other. (System Stakeholder 6: Nurse Practitioner)\u003c/p\u003e \u003cp\u003eStakeholders recognised unintended outcomes that might be considered as part of subsequent piloting, evaluation and implementation. These were the risk of creating dependency on outreach services for health support, which may later lack capacity. This could happen if transitions to mainstream healthcare services are not well managed.\u003c/p\u003e \u003cdiv id=\"Sec25\" class=\"Section3\"\u003e \u003ch2\u003eContext\u003c/h2\u003e \u003cp\u003eAll stakeholder groups acknowledged the initial eight context factors that might inhibit intervention functioning, while focusing discussion on four. These were not necessarily deemed more important, but rather needing additional in-depth description. An additional two context factors were identified.\u003c/p\u003e \u003cp\u003eFirst, the context factor of geographical location of service users. In addition to the geographical dispersal of individuals within a service area, lived experienced and professional stakeholders explained the complications with them moving between areas. In such instances, they might move outside of the boundaries of certain health, social care and housing providers, making it impossible to ensure continuous provision. Equally, having individuals repeatedly recount their needs and histories may be re-traumatising, potentially leading to service disengagement.\u003c/p\u003e \u003cp\u003eSecond, was the context factor related to belief systems and discourses around homelessness. Professional stakeholders noted how people experiencing homelessness are stigmatised across the health care system, notably in hospitals. There are also complications where discourses differ between professional groups, which might inhibit interprofessional collaboration. As one system stakeholder stated:\u003c/p\u003e \u003cp\u003eThere can be tussles between different professional groups within the statutory sector, you know, there may not be similar ideas or understanding about risk or thresholds or pace of response\u0026hellip; (System Stakeholder 2: Homelessness Researcher)\u003c/p\u003e \u003cp\u003eThird, was the organisational capacity context factor. There is the potential not to recruit sufficiently qualified nurses, especially where there is a concentration in expertise in urban areas (e.g. London), and less of a potential workforce in more rural areas. Lived experience stakeholders raised concerns about the possibility for nurses to experience burnout during intervention delivery. They highlighted the emotional toll of supporting individuals who have experienced high levels of trauma, and managing mental health crises and other complex health and social needs. With limited organisational capacity to provide ongoing support, nurses may feel overwhelmed, leading to high staff turnover.\u003c/p\u003e \u003cp\u003eFourth, was the record maintenance and data sharing infrastructure context factor. Lived experienced stakeholders highlighted that population transience, such as the above trend for moving between areas, meant that data needed to be accessed by a range of professionals. However, there is often a lack of detailed and centralised record-keeping to support service continuity. System stakeholders maintained that IT infrastructure would need to be improved to ensure effective data sharing.\u003c/p\u003e \u003cp\u003eThe first new context factor was considered by the professional stakeholder group. This was the profile of individuals experiencing homelessness, and the fact that different intervention delivery areas may serve different populations. As such it could be difficult to deliver the intervention if the eligibility criteria were restricted to particular groups (e.g. rough sleeping), as this may place many in need service users out of scope.\u003c/p\u003e \u003cp\u003eThe second novel context factor, reported across all data sources, was the availability and accessibility of service provision in the wider health, social care and housing sectors. Lived experience stakeholders noted that nurses might signpost and refer service users to mainstream healthcare but were adamant that this was not helpful: it makes people feel they are being \u0026ldquo;gotton rid of\u0026rdquo;. They felt that where individuals live in precarious conditions, immediate needs take precedence, meaning continued engagement with a referral process may not be viable. All stakeholder groups felt nurses should be able to attend appointments with service users. There were related concerns about limited resources to attend appointments where services are only available in locations reachable by public transport, or if they require access to digital tools such as smartphones. This context factor is also relevant to discussion regarding the intervention outcome. Professional stakeholders and system stakeholder interviews recognised that in some areas, variations in service availability and community resources would likely influence whether nurses targeted health or housing outcomes, leading to inconsistency in practice across areas.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec26\" class=\"Section3\"\u003e \u003ch2\u003eFinal programme theory and operational delivery plan\u003c/h2\u003e \u003cp\u003eWe integrated findings from the refinement of programme theory phase into the candidate programme theory to generate the final programme theory. Overall professional stakeholders agreed with the final programme theory as an accurate description of how outreach with a health specialism should optimally work. Stakeholders also made some further clarifications to our understanding of the context factors, which are included in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eWe distilled findings to identify seven refinements to intervention components and implementation processes that will maximise the likelihood of specified mechanisms being activated. These were accompanied by an operational delivery plan. Professional stakeholders agreed with these recommendations. Only small points of clarification and additions were made.\u003c/p\u003e \u003cp\u003eIt is important to note that stakeholders provided few recommendations for modifying the context during the refinement of programme theory phase. Rather they focused on how the intervention could be changed to maximise functioning within system constraints. This may have been due to a perception that context factors could not be restructured as they are beyond the scope of the intervention team. Equally, stakeholders were not always clear exactly how context factors would interact with the intervention, and so articulating the exact modifications needed was a challenge. It may be easier to develop recommendations for contextual restructuring following the piloting phase, when we have empirical evidence as to how these interactions unfold.\u003c/p\u003e \u003cp\u003eThe final recommended intervention refinements, and plan to operationalise them, were:\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eLived experience voices in outreach nurse training\u003c/strong\u003e \u003cp\u003eBespoke training modules to include training with individuals who have lived experience. This will focus on role-playing, so that nurses can build confidence to engage with, and support, those with complex needs and a mistrust of healthcare systems. Training provider (SDS) to design training modules to include activities that support lived experience input.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eKey principles, skills and knowledge in outreach nurse training\u003c/b\u003e: Bespoke training modules to be aligned with key principles of: trauma-informed care (\u0026lsquo;meet people where they are\u0026rsquo;); building trust rather than dependence; empathy and understanding; tailoring provision to meet diverse needs; avoiding authoritarian language; and working in ways that prevent burnout. Key knowledge and skills learning to be included: (radical) safeguarding, mental health as a chronic disease (e.g. hoarding), management of common clinical conditions with discussions on clinical risk, communication strategies, reflective practice, cultural competence, and key legislation (e.g. housing law and the Care Act 2014). Training provider (SDS) to ensure core training modules are aligned with these principles and deliver skills. Where there is limited time to cover all additional skill sets, CGL to ensure nurses undertake training modules from portfolio of options available via the Queen\u0026rsquo;s Nurses Institute, the London Network of Nurses and Midwives, Fairhealth and Aneemo. CGL to construct job descriptions and appoint outreach nurses with demonstrable clinical and non-clinical skill sets that will enable them to work in accordance with intervention principles.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eSupportive supervision and community of practice\u003c/strong\u003e \u003cp\u003eSupervision to have clear focus on supporting wellbeing of nurses to avoid burnout and monitor nurses use of reflective practice. CGL to construct job description and appoint lead nurse with skill set to support nurse wellbeing. CGL to facilitate relationships between outreach nurses to build a supportive peer-led community of practice with knowledge and skill exchange. Lead nurse to monitor nurses training needs and support uptake to ensure continued capability and competency in role.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eTailoring outreach to service user needs\u003c/strong\u003e \u003cp\u003eNurses to be flexible in their approach. This includes being geographically mobile, visiting spaces that are safe and convenient for people who sleep rough, and adapting to the specific needs of each service user. The training provider (SDS) to ensure core training modules support flexibility. CGL to ensure supervision supports this tailored approach. However, core training, additional training and supervision must emphasise the need for some standardisation and parameters to ensure consistency, making sure nurses are working in accordance with the intervention\u0026rsquo;s underpinning causal mechanisms.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eEfficient data generation and flow\u003c/strong\u003e \u003cp\u003eNurses require appropriate and functioning equipment to undertake outreach. This includes technology to record service users\u0026rsquo; health and medical equipment to meet immediate needs. CGL to check and ensure that nurses have all required provision. Data storge and sharing within delivery organisation and with other institutions needs to be addressed. CGL to monitor data flow throughout pilot study, working to ensure efficiency and tackle issues.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eAttendance at service user appointments\u003c/strong\u003e \u003cp\u003eNurses should have ability and capacity to attend appointments with service users. Training provider (SDS) to emphasise this in core training modules and CGL to ensure supervision encourages this as resources allow.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConfidence and capability in service-follow up\u003c/strong\u003e \u003cp\u003eTo support service-follow up nurses need to feel confident to build relationships with health and non-health care sectors. Training provider (SDS) to support confidence and capability in service follow-up during core training modules. CGL to encourage this skill through supervision, reflective practice and peer-led community of practice, identifying additional training where relevant.\u003c/p\u003e \u003c/p\u003e \u003cp\u003eOn confirmation of the final programme theory, we agreed with the training provider (SDS) and CGL that the proposed modifications to the intervention components and implementation process would be viable. This was partly because proposals harnessed a large amount of existing resource from the wider infrastructure, for example accessing training modules from CGLs own catalogue or national nursing training networks. The final agreed programme theory is presented in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, in accordance with the TIDieR checklist and the associated logic model (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eTIDieR description of outreach with a health specialism intervention\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTIDieR Framework Component\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDescription\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBrief Name: Provide the name or a phrase that describes the intervention\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOutreach services with health specialism for people rough sleeping.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWhy: Describe any rationale, theory, or goal of the elements essential to the intervention\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eThe overarching rationale of the intervention is that nurses meet service users where they are rough sleeping, which increases contact with service users. Nurses have a respected identity as a health professional that service users may trust to support them. This trust can be enhanced by nurses having professional knowledge to identify and deliver the correct service provision and have the expertise and professional standing to secure service access. Nurses should be able to use clinical and legal literacy to advocate for the service user. Nurses\u0026rsquo; identification of a health care need for service users can also ensure access to appropriate accommodation, as health care needs can result in an accommodation entitlement. Multidisciplinary collaboration between nurses and other sectors can help to identify and secure appropriate follow-on services.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWhat (Materials): Describe any physical or informational materials used in the intervention, including those provided to participants or used in intervention delivery or in training of intervention providers. Provide information on where the materials can be accessed (such as online appendix, URL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTraining to include a combination of standard and bespoke training.\u003c/p\u003e \u003cp\u003e\u003cb\u003eStandard Training\u003c/b\u003e: Standardised training modules will be made available to nurses through CGL. Training providers will include QNI, LNNM, Fairhealth and Aneemo.\u003c/p\u003e \u003cp\u003e\u003cb\u003eBespoke Training\u003c/b\u003e: Nurses will receive a bespoke training package. Four half day training sessions will be delivered by the training provider (SDS). Two will be delivered online and two will be delivered in person. These will be complemented by a range of other electronic resources. \u003csup\u003ea\u003c/sup\u003e Training to include lived experience voices.\u003csup\u003ec\u003c/sup\u003e Knowledge and skill set should extend to include: (radical) safeguarding, mental health as a chronic disease (e.g. hoarding), management of common clinical conditions with discussions on clinical risk, communication strategies, reflective practice, cultural competence, and key legislation (e.g. housing law and the Care Act 2014).\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWhat (Procedures): Describe each of the procedures, activities, and/or processes used in the intervention, including any enabling or support activities\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003ePrinciples\u003c/b\u003e: Intervention to be flexible, responsive, person-centred, generalist, and adopt a broad understanding of rough sleeping.\u003c/p\u003e \u003cp\u003eThere are four key intervention components:\u003c/p\u003e \u003cp\u003e\u003cb\u003eOutreach nurse training\u003c/b\u003e: Includes standard and bespoke training.\u003c/p\u003e \u003cp\u003e\u003cb\u003eOutreach with health specialism shifts\u003c/b\u003e: Outreach nurses accompany outreach teams to deliver healthcare on the street and arrange access to follow-on services.\u003c/p\u003e \u003cp\u003e\u003cb\u003eOutreach nurse supervision\u003c/b\u003e: Clinical supervision of nurses by a lead nurse.\u003c/p\u003e \u003cp\u003e\u003cb\u003eService follow-up and Multi-disciplinary Team (MDT) meetings\u003c/b\u003e: Arrangement of follow-up healthcare and housing services after outreach shifts. Accompany service users to meetings if viable and appropriate. Attendance at MDT meetings to advocate for the service user.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWho provided: For each category of intervention provider (such as psychologist, nursing assistant), describe their expertise, background, and any specific training given\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eLead nurse\u003c/b\u003e\u003c/p\u003e \u003cp\u003eLead nurse to be based in CGL (equivalent to top NHS Band 8). Will line manage and supervise the trained outreach nurses (equivalent to top NHS Band 7). Lead nurses will provide clinical supervision and personal support to nurses.\u003c/p\u003e \u003cp\u003e\u003cb\u003eOutreach nurses\u003c/b\u003e\u003c/p\u003e \u003cp\u003eDesirable competencies for the outreach nurses include:\u003c/p\u003e \u003cp\u003e● An advanced assessment course and/or significant experience of clinical triage e.g. within an A\u0026amp;E department;\u003c/p\u003e \u003cp\u003e● History of working with people who have experienced homelessness;\u003c/p\u003e \u003cp\u003e● A proven ability to assess and manage clinical risk independently;\u003c/p\u003e \u003cp\u003e● Level 3 safeguarding training (including an understanding of self-neglect);\u003c/p\u003e \u003cp\u003e● Ability to directly prescribe (i.e. the ability to provide an immediate prescription) or to provide drugs by Patient Group Direction.\u003c/p\u003e \u003cp\u003eBased on previous case examples of outreach nurses, it has been suggested that they should be an NHS Band 7 equivalent to ensure they have the requisite experience and expertise (Dorney-Smith, N.D.).\u003c/p\u003e \u003cp\u003e\u003cb\u003eOutreach nurse training\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003eStandard training\u003c/b\u003e: Training will be facilitated by CGL and primarily provided through the QNI, LNNM, Fairhealth and Aneemo.\u003c/p\u003e \u003cp\u003e\u003cb\u003eBespoke training\u003c/b\u003e: Training will be developed by training provider (SDS) and hosted by CGL.\u003c/p\u003e \u003cp\u003e\u003cb\u003eOutreach teams\u003c/b\u003e\u003c/p\u003e \u003cp\u003eTypically 1\u0026ndash;2 members of the designated outreach team will accompany the nurses during the outreach shifts. The number of accompanying outreach workers can be negotiated, but the key is that outreach nurses should not go alone.\u003c/p\u003e \u003cp\u003e\u003cb\u003eOther professionals (for MDT meetings)\u003c/b\u003e\u003c/p\u003e \u003cp\u003eA range of partnering teams and professionals will be required to ensure that service users\u0026rsquo; complex needs can be met, and appropriate follow-on care can be planned. These can include, but are not limited to (Dorney-Smith, 2022):\u003c/p\u003e \u003cp\u003e● Local Authority rough sleeping pathway teams and their leads\u003c/p\u003e \u003cp\u003e● Local Authority housing teams\u003c/p\u003e \u003cp\u003e● Linked GPs and other primary care services\u003c/p\u003e \u003cp\u003e● Outreach and mainstream mental health teams\u003c/p\u003e \u003cp\u003e● Outreach and mainstream addictions teams\u003c/p\u003e \u003cp\u003e● Social care teams / Safeguarding teams including specialist Social Workers\u003c/p\u003e \u003cp\u003e● Police and Police Community Support Officers, transport police and security\u003c/p\u003e \u003cp\u003e● Parks attendants\u003c/p\u003e \u003cp\u003e● Various voluntary sector support services e.g. day centre providers\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHow: Describe the modes of delivery (such as face to face or by some other mechanism, such as internet or telephone) of the intervention and whether it was provided individually or in a group\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eOutreach nurse training\u003c/b\u003e: To be delivered in person and online.\u003c/p\u003e \u003cp\u003e\u003cb\u003eOutreach with health specialism shifts\u003c/b\u003e: To be delivered in person mainly on the street. Data entry and storage to be done electronically.\u003c/p\u003e \u003cp\u003e\u003cb\u003eOutreach nurse supervision\u003c/b\u003e: To be delivered in a group or individual format online or via telephone. May entail occasional in-person meetings.\u003c/p\u003e \u003cp\u003e\u003cb\u003eService follow-up and MDT meetings\u003c/b\u003e: To be delivered online, via telephone or in person depending on the services that outreach nurses follow-up with or the meetings they attend.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWhere: Describe the type(s) of location(s) where the intervention occurred, including any necessary infrastructure or relevant features\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eOutreach nurse training\u003c/b\u003e: Will be remotely delivered and accessed through the relevant platform. The venue for in-person training to be agreed.\u003c/p\u003e \u003cp\u003e\u003cb\u003eOutreach with specialism shifts\u003c/b\u003e: Will be delivered mainly on the street. Outreach teams will identify the location of the service users as they will have more experience and knowledge of their location. Nurses may attend other venues (e.g., soup kitchens) and health settings to enrol participants, facilitate follow-on care, or track participants.\u003c/p\u003e \u003cp\u003e\u003cb\u003eOutreach nurse supervision\u003c/b\u003e: Online meetings will be remotely accessed through the relevant platform. The venue of in-person meetings will likely be at CGL offices.\u003c/p\u003e \u003cp\u003e\u003cb\u003eService follow-up and MDT meetings\u003c/b\u003e: Online meetings will be remotely accessed through the relevant platform. In-person meetings will likely be accessed at the location of the services that outreach nurses follow-up with.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWhen and how much: Describe the number of times the intervention was delivered and over what period of time including the number of sessions, their schedule, and their duration, intensity, or dose\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eOutreach nurse training\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003eStandard training\u003c/b\u003e: Training to be made available to outreach nurses on an ongoing basis. CGL will arrange a hosting platform and training developer will share resources to be hosted alongside training modules provided by the Queens\u0026rsquo;s Nursing Institute, LNNM, Fairhealth and Aneemo training and resource platforms.\u003c/p\u003e \u003cp\u003e\u003cb\u003eBespoke training\u003c/b\u003e: Training to be delivered as four half day sessions. Two to be delivered online and two to be delivered in person.\u003c/p\u003e \u003cp\u003eNurses working week will be split as follows:\u003c/p\u003e \u003cp\u003e\u003cb\u003eOutreach with health specialism shifts (40% of week)\u003c/b\u003e:This should include a minimum of two shifts on the streets with service users, each take approximately seven to eight hours (approx. 15\u0026ndash;16 hours total). Outreach teams will need to be flexible at times providing out-of-hours care as service users can have transient schedules.\u003c/p\u003e \u003cp\u003e\u003cb\u003eOutreach nurse supervision (20% of week)\u003c/b\u003e: Lead nurse to meet with the outreach nurses collectively on a weekly basis. Each nurse will also have monthly (where possible) clinical supervision meetings with the lead nurse. Lead nurses across LAs may benefit from meeting regularly to share good practice and support. Additional community of practice activities to be considered during this time.\u003c/p\u003e \u003cp\u003e\u003cb\u003eService follow-up and MDT meetings (40%)\u003c/b\u003e: Nurses to ensure data and information are complete and to secure follow-up services. They may also be required to spend time attending MDT meetings. Where viable, nurses may accompany service users to meetings. Nurses also to spend time completing data collection for the pilot cluster Randomised Controlled Trial.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTailoring: If the intervention was planned to be personalised, titrated or adapted, then describe what, why, when, and how\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eThe intervention should always comprise delivery of the four components. In accordance with intervention principles, delivery should be flexible to meet the needs of individual service users and focus on responding to localised gaps in current outreach provision. Nurses should be aware of underpinning causal mechanisms to ensure any tailoring does not compromise intervention functioning.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eModifications: If the intervention was modified during the course of the study, describe the changes (what, why, when, and how)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTo be reported after completion of the pilot Randomised Controlled Trial.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHow well (Planned): If intervention adherence or fidelity was assessed, describe how and by whom, and if any strategies were used to maintain or improve fidelity, describe them\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eKey fidelity measures to include:\u003c/p\u003e \u003cp\u003e\u003cb\u003eOutreach nurse training\u003c/b\u003e\u003c/p\u003e \u003cp\u003e● Completion of standard and bespoke training.\u003c/p\u003e \u003cp\u003e\u003cb\u003eNurse outreach with health specialism shifts\u003c/b\u003e\u003c/p\u003e \u003cp\u003e● Delivery in outreach settings for approximately 15\u0026ndash;16 hours per week over two shifts\u003c/p\u003e \u003cp\u003e● Service user uptake of treatment/support offer\u003c/p\u003e \u003cp\u003e● Delivery of immediate treatment (where appropriate)\u003c/p\u003e \u003cp\u003e● Manageable caseloads\u003c/p\u003e \u003cp\u003e\u003cb\u003eOutreach nurse supervision and quality assurance\u003c/b\u003e\u003c/p\u003e \u003cp\u003e● Number of supervision sessions between Lead Nurse and nurses\u003c/p\u003e \u003cp\u003e\u003cb\u003eFollow-up services and MDT meetings\u003c/b\u003e\u003c/p\u003e \u003cp\u003e● Number and range of follow-up services secured for service users (where appropriate)\u003c/p\u003e \u003cp\u003e● Uptake of follow-up service offer by service users\u003c/p\u003e \u003cp\u003e● Number of MDT meetings attended by outreach nurses\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHow well (actual): If intervention adherence or fidelity was assessed, describe the extent to which the intervention was delivered as planned\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTo be reported after completion of the pilot Randomised Controlled Trial.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eIn the present study we report one of the first systematic and empirically-driven descriptions of outreach with a health specialism. We have comprehensively described the intervention\u0026rsquo;s programme theory, eliciting the causal mechanisms, components, implementation processes, outcomes and context. This is an important contribution, as while outreach has been recommended by NICE guidance (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e), currently there is limited understanding of how the intervention should work or how it might interact with system characteristics in the generation of outcomes. In the study, we also identified several recommendations for refining components and implementation processes to optimise functioning.\u003c/p\u003e \u003cdiv id=\"Sec28\" class=\"Section2\"\u003e \u003ch2\u003eSummary of findings\u003c/h2\u003e \u003cp\u003eWe identified six mechanistic pathways through which outreach with a health specialism should bring about change. These mechanistic pathways target both housing and health outcomes. For example, outreach nurses may draw upon their legal literacy and advocacy skills to establish an accommodation entitlement based on their service users\u0026rsquo; health status. This targeting of multiple inter-related outcomes is vital due to the extensive evidence supporting the bi-directional relationship between housing and health in homeless populations. Individuals with poor health outcomes, such as an acquired brain injury, are less likely to obtain stable housing (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). Meanwhile, a focus on meeting physiological needs, such as shelter, can ensure healthcare uptake is prioritised (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAs part of the study, we optimised intervention components and implementation processes. Central to the refinement process was extending the knowledge and skill base of nurses to ensure competency in working with a range of people with different characteristics and experiences of health and housing services. Strengthening confidence and capability in service-follow up and engagement with other health, social care and housing services was also key. This is justified by a recent evaluation of different healthcare models for supporting outcomes for individuals experiencing homelessness (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e). The study found that mobile outreach teams often struggled with collaborative working, leading to uncertainty and confusion among patients and low levels of continuity in care. However, where GPs were part of the mobile team, and care provision across health professionals was fully integrated, continuity in care rates were higher. We also identified that outreach provision would need to be flexible and tailored to achieve acceptability among service users. This is supported elsewhere in the evidence-base (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eWe generated context factors that may inhibit intervention functioning. Given that much of the existing research on outreach is from the USA and Australia, these findings offer a significant contribution to the more limited understanding of how the wider health, social care and housing system could influence the effectiveness of health outreach in the UK (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e). Key context factors include variations in population characteristics, limited organisational capacity, and availability of follow-on services. As noted, stakeholders generally did not focus on restructuring the context during recommendations for refinements, rather describing them as entrenched barriers. It is important to consider further how these context factors can be effectively tackled, amidst calls for intervention efforts to be supported by upstream re-structuring (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec29\" class=\"Section2\"\u003e \u003ch2\u003eImplications for policy and practice\u003c/h2\u003e \u003cp\u003eThe findings of the study, combined with the subsequent pilot cluster Randomised Controlled Trial, will provide important learning to help inform future policy-making and practice. Our optimised model provides a mechanism for realising NICE and NHS Long Term Plan recommendations for an integrated, multidisciplinary approach to mitigating health inequalities (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e). Importantly, we have shown how the intervention might target the dual outcomes of health and housing, both of which are key policy priorities for this population (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e). To support this type of approach moving forward, there is an imperative need for workforce development, particularly in terms of the training and retention of nurses with advanced clinical and legal competencies, a sentiment that aligns with the Queen\u0026rsquo;s Nursing Institute (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e) proposal for specialist training in inclusion health.\u003c/p\u003e \u003cp\u003eThe study further provides useful implications for practitioners. A central thread of our findings was the need to foreground the voices of lived experience individuals in training and delivery to ensure professionals can meet complex and diverse needs. This resonates with NICE guidelines for people experiencing homelessness, which recommend co-production in service design (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e). We also recognise the need for tailoring services to the need of target populations. However, this needs to be undertaken within specified parameters, and there is value in having practitioners be familiar with the underpinning mechanisms of interventions, so they are aware when local modifications are compromising the programme theory and risking outcomes. Finally, to support integrated and inter-professional care, nurses need to be trained and empowered to engage in the complex health, social care and housing landscape, receiving ongoing supervision and training as required.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eImplications for future research\u003c/h3\u003e\n\u003cp\u003eThe study has important research implications. It offers a worked case example of how interventions can be optimised, and the value of optimisation in maximising the likelihood of an intervention functioning. While optimisation is clearly defined and operationalised within optimisation research designs such as MOST (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e), there is less understanding of how optimisation fits with other evaluation frameworks. We have demonstrated how optimisation can be undertaken as part of the first phase of the Medical Research Council guidance on the development and evaluation framework (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). There is a need to continue to make methodological progress on how to conduct optimisation in alignment with the guidance, potentially with a view to developing frameworks similar to those that have been produced for intervention development (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn terms of the outreach with a health specialism intervention, there is an ongoing need to strengthen the evidence-base. This will be partly addressed by the pilot cluster Randomised Controlled Trial that follows this optimisation study. Future research needs to focus on testing the causal power of the mechanisms we have proposed, identifying additional mechanisms, and examining if these mechanisms may generate unanticipated and even harmful outcomes alongside the intended impacts. Relatedly, further work is required to establish the full complement of outcomes that are theoretically appropriate for this intervention approach. This includes building evidence of effect sizes for different outcomes. It also means generating process evaluation data to understand if local systems and stakeholders can simultaneously target multiple outcomes or if they tend to deliver the intervention in a way that prioritise certain impacts (e.g. healthcare uptake rather than appropriate accommodation). Finally, as a central principle of the intervention is to achieve flexibility and tailoring, there needs to be a focus on using appropriate methods for defining and evaluating non-standardised approaches. The growing literature on adaptive and just-in-time adaptive public health interventions may be supportive here, along with frameworks for assessing fidelity to mechanisms rather than components (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e).\u003c/p\u003e \u003cdiv id=\"Sec31\" class=\"Section2\"\u003e \u003ch2\u003eStrengths and limitations\u003c/h2\u003e \u003cp\u003eThere are a number of strengths and limitations that should be taken into account when interpreting the study findings. The study benefited from a range of stakeholders engaged across the homeless sector in the UK, including those with lived experience. This enabled us to generate rich insights into the intervention delivery context, particularly from system stakeholders who had a history of implementation. We would have benefited from further involvement of lived experience stakeholders, as the contribution of participating individuals was extremely useful. We will continue to prioritise understanding their experiences of intervention participation during the process evaluation embedded in the pilot trial. The study was further strengthened by the sequential and integrated approach to data collection, where findings from each stakeholder group could feed into discussion with the next. This allowed us to explore consistencies and discrepancies in understanding and views between stakeholder groups. It was particularly useful to return to the stakeholder professional group to confirm the final programme theory, as we were able to verify if the intervention description and optimisation process had accurately responded to feedback. We would have benefitted from confirming the final programme theory with lived experience and system stakeholders, but unfortunately time did not allow.\u003c/p\u003e \u003c/div\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eOutreach has been recommended by NICE guidance as a potentially effective approach for targeting healthcare uptake among individuals experiencing homelessness. In this study we described and optimised the programme theory for outreach with a health specialism, identifying the causal mechanisms which explain how the intervention may target both health and accommodation. A comprehensive description of the programme theory is important for future evaluation, as it clarifies the intervention that evaluators are making evidence-based claims about. Our recommendations for optimising intervention components and implementation processes will support nurses and other professionals in developing, implementing and adapting interventions for delivery with individuals experiencing homelessness.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthical approval is provided by Cardiff University School of Medicine Research Ethics Committee (REF: 24/38). Informed consent was obtained by individuals\u0026nbsp;participating\u0026nbsp;in system stakeholder interviews. The study was conducted in accordance with the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe Ministry of Housing, Communities and Local Government (MHCLG) is the \u0026ldquo;data controller\u0026rdquo;. The privacy notice for the study is reported here: https://www.gov.uk/government/publications/homelessness-and-rough-sleeping-outreach-with-a-health-specialism-privacy-notice/homelessness-and-rough-sleeping-outreach-with-a-health-specialism-privacy-notice#storage-security-and-data-management. Further information about data availability can be obtained by contacting the MHCLG.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSam Dorney-Smith was commissioned by the Centre for Homelessness Impact as an Independent Advisor to the Test and Learn Programme. She supported the delivery of stakeholder workshops. She was funded through Inclusion Nursing to deliver the training component of the intervention. Funding was not contingent on the content or implementation strategy of the training components, which were partly developed and refined through the optimisation workshops.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work has been funded by the Ministry of Housing, Communities and Local Government (MHCLG) via the Centre for Homelessness Impact (CHI) as part of the Test \u0026amp; Learn and Systems-Wide Evaluation Programme, a \u0026pound;15m programme of work to improve the evidence base and understanding of what works to end rough sleeping. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical Trial Number\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eISRCTN11572394\u0026nbsp;(13/12/2024)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eR.E., P.M., L.A., Y.M., R.B., and J.W. led the conceptualisation and design of the study. \u0026nbsp;R.E., P.M., L.A., S.D.S. and J.W. led the acquisition of data, analysis of data and interpretation of data. R.E. led the drafting of the manuscript. \u0026nbsp;All authors reviewed the manuscript, revising it critically for important intellectual content.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors are grateful to all stakeholders who have contributed to the study. We are grateful to Christopher Usborne, Centre for Trials Research, School of Medicine, Cardiff University who has provided professional service support for the study.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eFornaro M, Dragioti E, De Prisco M, Billeci M, Mondin AM, Calati R, et al. Homelessness and health-related outcomes: an umbrella review of observational studies and randomized controlled trials. BMC Med. 2022;20(1):224.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAldridge RW, Story A, Hwang SW, Nordentoft M, Luchenski SA, Hartwell G, et al. 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Thematic analysis: A practical guide. 2021.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHoffmann TC, Glasziou PP, Boutron I, Milne R, Perera R, Moher D, et al. Better reporting of interventions: template for intervention description and replication (TIDieR) checklist and guide. BMJ: Br Med J. 2014;348:g1687.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePratt B. What are Important Ways of Sharing Power in Health Research Priority Setting? Perspectives From People With Lived Experience and Members of the Public. J Empir Res Hum Res Ethics. 2021;16(3):200\u0026ndash;11.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStubbs JL, Thornton AE, Sevick JM, Silverberg ND, Barr AM, Honer WG, et al. Traumatic brain injury in homeless and marginally housed individuals: a systematic review and meta-analysis. Lancet Public Health. 2020;5(1):e19\u0026ndash;32.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCrane M, Joly L, Daly BJ, Daly B, Gage H, Manthorpe J, et al. Integration, effectiveness and costs of different models of primary health care provision for people who are homeless: an evaluation study. Health social care delivery Res. 2023;11(16):1\u0026ndash;217.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCrane M, Joly L, Daly BJ, Gage H, Manthorpe J, Cetrano G, et al. Primary health care for people experiencing homelessness: the effectiveness of specialist and mainstream health service provision. Br J Gen Pract. 2024;74(749):568.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePadgett DK. Homelessness, housing instability and mental health: making the connections. BJPsych Bull. 2020;44(5):197\u0026ndash;201.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDepartment of Health and Social Care. 10 Year Health Plan for England: Fit for the future. London: Department of Health and Social Care; 2025.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHurst G, Teizeira L, Davies N. A smarter apporach to homelessness: prioritising prevntion in the 2025 spending review. London: Centre for Homlessness Impact; 2025.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eQueen\u0026rsquo;s Nursing Institute. Homeless inclusion nurses - Practitioners addressing inequalities in health. London: Department of Health \u0026amp; Social Care; 2022.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCollins LM, Murphy SA, Strecher V. The multiphase optimization strategy (MOST) and the sequential multiple assignment randomized trial (SMART): new methods for more potent eHealth interventions. Am J Prev Med. 2007;32(5 Suppl):S112\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eO\u0026rsquo; Cathain A, Croot L, Duncan E, Rousseau N, Sworn K, Turner KM, et al. Guidance on how to develop complex interventions to improve health and healthcare. BMJ Open. 2019;9(8):e029954.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eP\u0026eacute;rez D, Van der Stuyft P, Zabala MC, Castro M, Lef\u0026egrave;vre P. A modified theoretical framework to assess implementation fidelity of adaptive public health interventions. Implement Sci. 2016;11(1):91.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZainal NH, Liu X, Leong U, Yan X, Chakraborty B. Bridging Innovation and Equity: Advancing Public Health Through Just-in-Time Adaptive Interventions. Annu Rev Public Health. 2025;46.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-health-services-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bhsr","sideBox":"Learn more about [BMC Health Services Research](http://bmchealthservres.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/BHSR/default.aspx","title":"BMC Health Services Research","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"homelessness, outreach, nurses, intervention, evaluation, development, optimisation","lastPublishedDoi":"10.21203/rs.3.rs-8855118/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8855118/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003ePeople who experience homelessness report poorer health outcomes than those who are housed. Outreach with a health specialism is an intervention aiming to remove barriers to healthcare by having health professionals deliver services directly to people in their own environment. Despite widespread use, currently there is limited evaluation evidence for the intervention in the UK. This study describes the intervention\u0026rsquo;s programme theory and reports the optimisation of components, implementation strategy and context to maximise intervention functioning across the UK health and housing system. It will be followed by a pilot cluster Randomised Controlled Trial with nested process and economic evaluation.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe conducted a mixed-method optimisation study in England between June 2024 and January 2025. The optimisation process comprised three research phases: development of candidate programme theory; refinement of programme theory; and confirmation of final programme theory and development of operational delivery plan. Research methods employed across optimisation phases were: rapid evidence review of intervention manual, training materials and evidence-base; three professional (n\u0026thinsp;=\u0026thinsp;12 individuals) and lived experience (n\u0026thinsp;=\u0026thinsp;7 individuals) stakeholder workshops; and semi-structured interviews with system stakeholder with experience of the intervention (n\u0026thinsp;=\u0026thinsp;8). The final optimised intervention was reported according to the Template for Intervention Description and Replication (TIDieR) checklist.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe programme theory describes intervention mechanisms, components, outcomes and context. We identified potential system inhibitors to intervention functioning in the UK, which include local variations in population profile, limited organisational capacity and availability of follow-on services. Recommendations for intervention optimisation were: integrating lived experienced voices into training; ensuring training aligns with person-centred, responsive, and trauma-informed principles; tailoring outreach; developing supervision and a peer-led community of practice; improving data generation and flow; nurses to attend appointments with clients; and empowering nurses to work with other sectors.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThis is one of the first studies to generate a comprehensive programme theory for outreach with a health specialism and describe how it can be optimally delivered in the UK. A clear theoretical understanding of how and why the should work will support future outcome evaluation and potential scale-up. It also provides a useful methodological example of intervention optimisation.\u003c/p\u003e\u003ch2\u003eTrial registration:\u003c/h2\u003e \u003cp\u003eISRCTN Registry ISRCTN11572394 (Registration 13/12/2024)\u003c/p\u003e","manuscriptTitle":"Outreach services with a health specialism for people rough sleeping in the UK: An intervention optimisation study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-20 16:25:33","doi":"10.21203/rs.3.rs-8855118/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"286873040200176458092945630238196562825","date":"2026-03-27T11:06:48+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"178169066583892977110587826196929682122","date":"2026-03-23T08:42:46+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-18T08:12:51+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-16T09:13:15+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-02-24T13:25:13+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-24T13:08:59+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Health Services Research","date":"2026-02-24T13:02:31+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-health-services-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bhsr","sideBox":"Learn more about [BMC Health Services Research](http://bmchealthservres.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/BHSR/default.aspx","title":"BMC Health Services Research","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5e5911f9-4d34-4c9c-84b6-98d9d1c85d56","owner":[],"postedDate":"March 20th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-20T16:25:33+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-20 16:25:33","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8855118","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8855118","identity":"rs-8855118","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}