The Care-Full Study: assessing the feasibility of a mixed-method longitudinal data collection approach for unpaid carers of people with multiple long-term conditions

Unpaid carers, Longitudinal data collection, Survey Methodology, Mixed-methods research, Peer researcher, Feasibility ALL Metrics - Views Downloads How to cite this article Jin H, Green R, Sanders F et al. The Care-Full Study: assessing the feasibility of a mixed-method longitudinal data collection approach for unpaid carers of people with multiple long-term conditions [version 1; peer review: 2 approved with reservations]. NIHR Open Res 2026, 6:14 (https://doi.org/10.3310/nihropenres.14229.1) NOTE: If applicable, it is important to ensure the information in square brackets after the title is included in all citations of this article. Export Citation Sciwheel EndNote Ref. Manager Bibtex ProCite Sente Select a format first ▬ ✚

Article [version 1; peer review: 2 approved with reservations] Haomiao Jin https://orcid.org/0000-0001-8908-1959 1, Richard Green https://orcid.org/0000-0001-6141-5910 1, Frances Sanders1, [...] Alex Penn https://orcid.org/0000-0001-5107-2862 2, Sotiris Moschoyiannis https://orcid.org/0000-0002-0164-8322 3, Gustavo Carneiro3, Tao Chen4, Heather Gage5, Morro Touray5, Caroline Nicholson1Haomiao Jin https://orcid.org/0000-0001-8908-1959 1, Richard Green https://orcid.org/0000-0001-6141-5910 1, [...] Frances Sanders1, Alex Penn https://orcid.org/0000-0001-5107-2862 2, Sotiris Moschoyiannis https://orcid.org/0000-0002-0164-8322 3, Gustavo Carneiro3, Tao Chen4, Heather Gage5, Morro Touray5, Caroline Nicholson1 PUBLISHED 16 Feb 2026 Author details Author details 1 School of Health Sciences, University of Surrey Faculty of Health and Medical Sciences, Guildford, England, UK 2 School of Engineering and Informatics, University of Sussex, Brighton, England, UK 3 School of Computer Science and Electronic Engineering, University of Surrey Faculty of Engineering and Physical Sciences, Guildford, England, UK 4 School of Chemistry and Chemical Engineering, University of Surrey Faculty of Engineering and Physical Sciences, Guildford, England, UK 5 School of Biosciences, University of Surrey Faculty of Health and Medical Sciences, Guildford, England, UK 2 School of Engineering and Informatics, University of Sussex, Brighton, England, UK 3 School of Computer Science and Electronic Engineering, University of Surrey Faculty of Engineering and Physical Sciences, Guildford, England, UK 4 School of Chemistry and Chemical Engineering, University of Surrey Faculty of Engineering and Physical Sciences, Guildford, England, UK 5 School of Biosciences, University of Surrey Faculty of Health and Medical Sciences, Guildford, England, UK Haomiao Jin Roles: Conceptualization, Data Curation, Formal Analysis, Funding Acquisition, Investigation, Methodology, Resources, Software, Validation, Visualization, Writing – Original Draft Preparation Roles: Conceptualization, Data Curation, Formal Analysis, Funding Acquisition, Investigation, Methodology, Resources, Software, Validation, Visualization, Writing – Original Draft Preparation Richard Green Roles: Conceptualization, Funding Acquisition, Investigation, Methodology, Project Administration, Resources, Writing – Original Draft Preparation Roles: Conceptualization, Funding Acquisition, Investigation, Methodology, Project Administration, Resources, Writing – Original Draft Preparation Frances Sanders Roles: Data Curation, Formal Analysis, Investigation, Project Administration, Resources, Software, Validation, Visualization, Writing – Original Draft Preparation Roles: Data Curation, Formal Analysis, Investigation, Project Administration, Resources, Software, Validation, Visualization, Writing – Original Draft Preparation Alex Penn Roles: Conceptualization, Funding Acquisition, Investigation, Methodology, Resources, Writing – Review & Editing Roles: Conceptualization, Funding Acquisition, Investigation, Methodology, Resources, Writing – Review & Editing Sotiris Moschoyiannis Roles: Conceptualization, Funding Acquisition, Investigation, Project Administration, Resources, Supervision, Writing – Review & Editing Roles: Conceptualization, Funding Acquisition, Investigation, Project Administration, Resources, Supervision, Writing – Review & Editing Gustavo Carneiro Roles: Conceptualization, Funding Acquisition, Writing – Review & Editing Roles: Conceptualization, Funding Acquisition, Writing – Review & Editing Tao Chen Roles: Conceptualization, Funding Acquisition, Writing – Review & Editing Roles: Conceptualization, Funding Acquisition, Writing – Review & Editing Heather Gage Roles: Conceptualization, Funding Acquisition, Methodology, Writing – Review & Editing Roles: Conceptualization, Funding Acquisition, Methodology, Writing – Review & Editing Morro Touray Roles: Methodology, Writing – Review & Editing Roles: Methodology, Writing – Review & Editing Caroline Nicholson Roles: Conceptualization, Funding Acquisition, Investigation, Methodology, Project Administration, Resources, Supervision, Writing – Original Draft Preparation Roles: Conceptualization, Funding Acquisition, Investigation, Methodology, Project Administration, Resources, Supervision, Writing – Original Draft Preparation OPEN PEER REVIEW REVIEWER STATUS Research on unpaid carers often relies on survey and interview data that are cross-sectional or infrequently repeated, providing limited insight into how carers’ experiences and wellbeing evolve over time. Combining frequent longitudinal surveys with regular qualitative check-ins offers a promising mixed-method approach for capturing change, yet there is limited evidence on the feasibility of implementing such data collection strategies over extended periods. As part of the NIHR-funded Care-Full study, we tested the feasibility of a mixed-method longitudinal data collection approach combining fortnightly digital self-report surveys with monthly qualitative check-ins facilitated by trained peer researchers with lived experience of caring. Fifteen unpaid carers were recruited across three sites in England and followed for up to ten months. Feasibility outcomes included recruitment and retention, completion rates, data missingness, engagement with an event-triggered “point of change” mini-survey component, and participant feedback on research participation, accessibility, and data collection approaches. Engagement with routine longitudinal data collection was high. No participants withdrew for reasons related to study burden, and completion of fortnightly surveys exceeded 93%, with minimal missing data across key measures of quality of life, health, and caregiving activities. The event-triggered “point of change” survey component proved difficult to implement in practice, with delayed reporting and lower completion rates, and was discontinued after four months. Monthly peer-researcher check-ins were consistently valued by participants, supporting sustained engagement and enabling contextualisation of survey responses over time. This feasibility study demonstrates that a mixed-method longitudinal approach combining regular digital surveys with peer-researcher engagement can support sustained data collection with unpaid carers over extended periods. Predictable, low-burden survey schedules were feasible, while regular peer-facilitated qualitative engagement enhanced the interpretability of longitudinal data. The findings provide methodological insights to inform future research seeking to collect longitudinal data on carers’ experiences and wellbeing over time. Many people in the UK provide unpaid care for family members or friends who are living with long-term health conditions. While this caring role is essential, it can have a big impact on carers’ own health, wellbeing, work, and daily life. However, most research with unpaid carers only collects information once or twice a year, which makes it hard to understand how caring experiences change over time. This study explored whether it is possible to collect information from unpaid carers more regularly, without placing too much burden on them. As part of a larger study funded by the National Institute for Health and Care Research (NIHR), 15 unpaid carers from different parts of England took part for up to ten months. They completed online surveys every two weeks about their health, quality of life, and caring activities. In addition, they had monthly conversations with trained peer researchers who had personal experience of being carers themselves. The study found that carers were very willing to take part over a long period. Most surveys were completed, very little information was missing, and no one stopped taking part because the study felt too demanding. Carers especially valued the monthly conversations with peer researchers, saying these helped them feel understood and gave them a chance to explain their survey answers in more detail. A separate study component that asked carers to report sudden changes in their situation was harder to use and was later stopped. Overall, the study shows that regular online surveys combined with supportive peer conversations are a practical and acceptable way to understand carers’ experiences over time. This approach could help future research and services better respond to carers’ changing needs. Unpaid carers, Longitudinal data collection, Survey Methodology, Mixed-methods research, Peer researcher, Feasibility Corresponding Author(s) Haomiao Jin ([email protected]) Grant information: The author(s) declared that no grants were involved in supporting this work. Copyright: © Crown copyright, 2026 Jin H et al.. This open access work is licensed under the Open Government Licence v3.0 How to cite: Jin H, Green R, Sanders F et al. The Care-Full Study: assessing the feasibility of a mixed-method longitudinal data collection approach for unpaid carers of people with multiple long-term conditions [version 1; peer review: 2 approved with reservations]. NIHR Open Res 2026, 6:14 (https://doi.org/10.3310/nihropenres.14229.1) First published: 16 Feb 2026, 6:14 (https://doi.org/10.3310/nihropenres.14229.1) Latest published: 16 Feb 2026, 6:14 (https://doi.org/10.3310/nihropenres.14229.1) Unpaid carers play a critical role in supporting older adults with multiple long-term conditions. In the UK, an estimated 5.7–6.5 million people (about one in ten adults) provide unpaid care for ill, disabled, or older family members, contributing an economic value on the order of £132–162 billion per year.1,2 This “hidden workforce” underpins health and social care systems, often compensating for shortfalls in formal care. However, caregiving frequently takes a personal toll – many carers experience deteriorations in their own health and quality of life due to the emotional, physical, and financial pressures of the role.1 Studies consistently find that carers have elevated rates of stress, depression, and anxiety compared to non-carers.3,4 Unpaid carers commonly feel insufficiently supported and “taken for granted,” indicating a gap between their needs and the support available from health and care services.2 These challenges underscore the importance of robust research to understand carer well-being and to inform better support – especially for those caring for older people with complex, multiple conditions. Research on unpaid carers in the UK has employed a mix of quantitative and qualitative methods to capture different facets of the caregiving experience. On the quantitative side, large-scale surveys are frequently used to measure key domains such as carers’ health status, quality of life, burden of care, and service use. For example, longitudinal panel studies like Understanding Society include modules where respondents report caregiving activities and their own health-related quality of life.5 In social care research, carer-specific outcome tools like the Adult Social Care Outcomes Toolkit for Carers (ASCOT-Carer)6 or the Adult Carer Quality of Life (Ac-QoL) instrument7 have been used to assess domains such as quality of life, psychological well-being, social isolation, and satisfaction with services. Routine national surveys (for example, the NHS biennial Survey of Adult Carers in England8) typically ask about carers’ quality of life, health, stress levels, hours of care, and experiences in navigating health and social care systems. These quantitative approaches yield broad indicators of carer outcomes and needs across large samples. On the qualitative side, in-depth methods like interviews and focus groups are widely employed to capture the lived experience of caring, enabling carers to discuss challenges and share insights.4 More recently, participatory and co-design methods have gained traction. Carers are involved as active partners in research design or data collection – for example, nominal group techniques and workshops where carers help set research priorities or develop survey content.4 In some emerging research, carers (including former carers) have even been trained as peer researchers to conduct interviews or “check-in” conversations with other carers, leveraging their shared experience to build trust.9,10 Such peer or co-research approaches acknowledge that carers’ insider perspective can enrich data collection and make participants more comfortable opening up. Despite the breadth of methods used, important limitations remain in how data on unpaid carers are collected. One major gap is the temporal infrequency of data collection in many studies. Much evidence about carers relies on cross-sectional snapshots or surveys administered at widely spaced intervals. For instance, national surveys or longitudinal cohort studies often collect carer data only at a single time point or at yearly/biennial waves, which can overlook the day-to-day realities of caregiving.5,8 Caregiving for an older person with multiple conditions is dynamic – health crises, fluctuations in the cared-for person’s needs, or sudden changes in support can occur with little warning. Research that only samples experiences annually or sporadically will miss these important short-term variations. Similarly, retrospective questions that ask caregivers to recall events or caregiving intensity over long periods (e.g. “in the last 5 years”) are prone to recall bias and imprecision.11 Moreover, classic qualitative data collection like interviews or focus group are rarely repeated over an extended period. These issues highlight that infrequent assessment or retrospective data collection with long recall period can fail to capture the true dynamics of caregiving experiences, potentially underestimating certain stresses or needs. Another limitation is that carers’ lived experiences are not always adequately represented in either research design or the resulting data. Quantitative carer surveys typically focus on broad outcomes such as quality of life and wellbeing, but often lack the granularity needed to capture the fluctuating, day-to-day realities of caregiving. In contrast, qualitative methods such as in-depth interviews or focus groups can generate rich insights but are frequently time-intensive, making them impractical for carers who provide ongoing care without respite.4 Moreover, carers may feel more comfortable sharing their experiences in formats that are flexible, responsive to their individual circumstances, and facilitated by individuals with shared caregiving experience, which is not always achievable within conventional research approaches.9,12,13 The limitations identified in existing carer research highlight the need for methodological innovation in how carers’ experiences are captured over time. In particular, there is a need for data collection approaches that are sufficiently frequent to reflect the dynamic nature of caregiving, flexible enough to minimise burden, and inclusive of carers’ lived experiences beyond what can be captured through standardised survey instruments alone. Advances in digital data collection, alongside growing recognition of the value of peer-research and participatory approaches, create new opportunities to address these challenges. As a part of the larger Care-Full study (award ID: NIHR158213), we designed a mixed-method longitudinal data collection approach that combines regular, low-burden quantitative surveys with ongoing qualitative engagement facilitated by peer researchers. Specifically, the approach integrates fortnightly self-report surveys alongside monthly check-ins conducted by trained peer researchers with lived experience of caregiving. This design aims to balance the strengths of quantitative and qualitative methods: providing repeated, structured measures over time while also creating space for carers to reflect on and contextualise their experiences in their own words. The primary aim of this paper is to assess the feasibility of this mixed-method approach, focusing on recruitment, retention, survey completion, missing data, and participant engagement over time, as well as the acceptability and perceived value of peer-researcher involvement. By reporting on these feasibility outcomes, the study seeks to inform the design of future longitudinal research with unpaid carers and contribute methodological insights into how mixed quantitative and qualitative data collection can be implemented in ways that are both rigorous and responsive to carers’ lived realities. Patients and members of the public, particularly unpaid carers of older people with multiple long-term conditions, were involved throughout the development and design of this study and continue to be actively involved in its conduct, governance, and dissemination. When and how were patients/public first involved in the research? Patient and Public Involvement and Engagement (PPIE) informed this study from its inception. The research design was directly shaped by learning from PPIE representatives and participants involved in previous NIHR-funded work within the same research programme, including the HEE/NIHR-funded PALLUP study (award ID: ICA-SCL-2018-04-ST2-001). These early discussions highlighted gaps in current support for unpaid carers, the complexity of caring for older people with multiple conditions, and the need for research approaches that better reflect carers’ real-world experiences. How were the research question(s) developed and informed by their priorities, experience, and preferences? The overarching research aims and questions were informed by carers’ priorities around recognising unpaid caring as a core component of home-based care systems, understanding key events and stress points in the caring journey, and identifying opportunities for earlier and more equitable support. PPIE input emphasised the importance of focusing on outcomes that matter to carers themselves, alongside outcomes for the older people they support, and the need to minimise burden while enabling meaningful participation over time. These perspectives directly shaped the study’s focus on mixed-method longitudinal data collection approaches that can reflect complexity and dynamic nature in unpaid caregiving. How were patients/public involved in the design and conduct of the study? Patients and the public were involved in multiple aspects of study design and conduct. PPIE representatives contributed to the development of participant-facing materials, including participant information sheets and consent processes, ensuring accessibility and clarity. The study governance structure includes PPIE representation through a Project Steering Group, providing oversight of study progress, ethics, and data management. A distinctive feature of the study is the involvement of unpaid carers as peer researchers. Current or recently former unpaid carers were invited to take on this role and receive training and support to contribute to data collection and participant engagement for the longitudinal workstream. Their involvement supported both the research process and a more equitable and reciprocal research relationship. How were patients/public involved in the choice of outcome measures? The selection of outcomes and data to be collected was informed by participatory systems mapping workshops involving unpaid carers, carer advocates, and other stakeholders. These workshops enabled carers to identify outcomes they considered most meaningful, such as wellbeing, burden, sustainability of caring, and interactions with health and social care services. PPIE representatives also contributed feedback on proposed survey content and data collection tools, which were iteratively refined to ensure relevance, acceptability, and minimal burden. How were patients/public involved in recruitment to the study? Patients and public contributors supported recruitment through existing PPIE networks, voluntary and community organisations, and previous research cohorts where consent to re-contact had been given. Recruitment strategies were designed with PPIE input to be flexible and sensitive to carers’ time constraints, using a combination of open, snowball, and targeted approaches facilitated by trusted gatekeeper organisations. How were patients/public be involved in choosing methods and agreeing plans for dissemination? Patients and public contributors were involved in shaping the participatory and longitudinal methods used in the study, including the format, timing, and delivery of workshops and interviews. Plans for dissemination have also been informed by PPIE priorities, with an emphasis on sharing findings in accessible formats with participants and relevant communities. Study findings will be fed back to participants who wish to receive them through summary reports, and dissemination activities will include events involving carers, stakeholders, and partner organisations. Co-production with PPIE representatives will continue to guide decisions about how results are communicated and how learning from the study is shared beyond academic outputs. This study employed a mixed-method approach to collect repeated quantitative and qualitative data from unpaid carers. The approach combined fortnightly self-report surveys with regular qualitative check-ins conducted by trained peer researchers. Quantitative data were primarily collected through a study-specific digital survey hosted on Qualtrics and accessible via smartphone or web browser. This digital format was selected to maximise accessibility and flexibility and to reduce the logistical burden associated with repeated data collection. Survey content and design were developed iteratively in collaboration with a data consultation group and PPIE contributors, with at least two rounds of testing and refinement conducted with unpaid carers prior to feasibility testing. This process aimed to ensure clarity, relevance, and acceptability of survey items while keeping completion time as short as possible. In addition to routine fortnightly surveys accessed by a specific link for each participant, the study incorporated an event-initiated data collection component. Participants were asked to notify the research team if a significant “point of change” occurred, such as a deterioration in the physical or mental health of the carer or the person being cared for (e.g. acute illness, falls, or hospitalisation). Following researcher review of the reported event, participants were invited to complete a series of brief daily micro-surveys for five consecutive days, covering a simplified subset of the fortnightly survey measures. This component was designed to capture short-term changes in carers’ wellbeing and caregiving demands during periods of heightened disruption. Following survey development, the full data collection protocol was tested for feasibility with 15 unpaid carers. Feasibility outcomes included recruitment and retention, survey completion rates, non-response, and missing data patterns. Participants were recruited across three study sites in England (West Sussex, South London, and Bradford) using a multi-pronged strategy designed to maximise reach and reduce burden for unpaid carers. Recruitment routes included open advertisement via regional and national voluntary and community sector organisations, snowball sampling through existing participants, and targeted recruitment from pre-identified cohorts from previous and ongoing studies where consent to re-contact had been provided. Local gatekeepers played a key role in site-specific recruitment, with formal gatekeeper approval obtained prior to recruitment through the following organisations: Carers Support (West Sussex), St Christopher’s Hospice (South London), and Health Action Local Engagement (Bradford). Participants who expressed an interest in participating in the study via email to the study team were sent the participant information sheet and invited to participate in a screening call, where they were informed about the study, and their eligibility and suitability was assessed against the inclusion criteria. Following a successful screening these potential participants were sent details for joining a baseline assessment and the link to an online consent form for completion at the beginning of the baseline assessment call or prior to the call if they wished. Participants were offered remuneration in recognition of their time and contribution, in line with NIHR guidance. Participants taking part in participatory mapping workshops and interviews received a £50 gift voucher. Members of the longitudinal cohort were remunerated over the 12-month study period with an initial £30 voucher followed by monthly £20 vouchers (total £270). Participants were also offered two coaching sessions regarding their unpaid caring responsibilities with a trained coach. The voucher and coaching offers were optional and reflected the extended and ongoing nature of participants’ involvement in this longitudinal study. This approach aimed to promote reciprocity, equity, and sustained engagement across all participant groups. Baseline data were collected at the start of the study to capture carers’ broader personal, social, and caregiving contexts. Baseline assessments were conducted via an online meeting with a member of the research team, according to participant preference, to support engagement and continuity in the study. The baseline assessment included qualitative measures and incorporated an eco-mapping exercise. During eco-mapping, participants were invited to draw and describe a visual map of key relationships with individuals, services, and organisations involved in their caregiving lives. These data were used to contextualise longitudinal survey responses, support interpretation of changes over time, and enable the development of individual case narratives across the study period. The baseline assessment also included an online survey covering all domains assessed in the longitudinal surveys (see below for details), alongside the collection of key background characteristics. These included demographic information (age group, gender, ethnicity, highest educational attainment, marital status, and employment status), prior caring experience, the relationship to the person being cared for, and current living arrangements. In addition, participants reported their use of formal and informal carer support services over the previous 12 months. The list of services was adapted from the Personal Social Services Survey of Adult Carers in England14 to ensure coverage of support types relevant within the UK care system. The longitudinal survey was informed by established survey methodology and drew on validated measures widely used in caregiving and health research. Measures were selected to balance psychometric robustness with feasibility for repeated administration. Key measures included in the survey are described below. Quality of Life Carer quality of life was assessed using the Adult Carer Quality of Life (AC-QoL) questionnaire.7 The AC-QoL measures eight domains reflecting both positive and negative aspects of caregiving: support for caring, caring choice, caring stress, financial implications, personal growth, sense of value, ability to care, and carer satisfaction. Each domain is assessed using multiple four-point Likert-scale items referring to experiences over the previous two weeks. Prior research has demonstrated good internal consistency and construct validity,7 including satisfactory convergent and discriminant validity with measures of burden, resilience, satisfaction, and physical and mental health, supporting its use among family carers. Health and Wellbeing General health status was assessed using a single-item self-rated health question with five response categories (excellent, good, average, poor, terrible). Symptoms of depression were measured using the eight-item Patient Health Questionnaire (PHQ-8),15 which assesses core symptoms of major depression over the previous two weeks. Additional wellbeing measures included self-reported average sleep duration and sleep quality over the past two weeks, and engagement in physical activity during the past week. Caregiving Activities and Work Impact Caregiving activities were grouped into three domains: 1. Activities supporting daily living of the person being cared for (e.g. personal care, meal preparation, transportation); 2. Activities related to coordinating medical or social care (e.g. scheduling appointments, communicating with service providers); 3. Activities supporting self-care of the person being cared for (e.g. medication management, monitoring symptoms). For each domain, participants reported typical time spent on activities over the previous three days, as well as the perceived mental and physical demands of these tasks during the same period. Work participation was assessed by asking participants to report the number of hours worked during the past week, hours of work missed due to caregiving or other reasons, and perceived impact of caregiving on productivity. These items were adapted from the Work Productivity and Activity Impairment Questionnaire: Informal Caregiving (WPAI:CG)16 and elements of the NASA Task Load Index (NASA-TLX).17 Peer researchers, referred to as Care-Full Companions, who were current or former unpaid carers recruited through existing PPIE contacts from past research projects, were supported through training and supervision and paid remunerated at an hourly rate aligned with NIHR payment guidance for public involvement in research. The role of these peer researchers was to conduct monthly check-ins with participants. Three peer researchers (two female, one male) were purposively recruited for prior experience in unpaid caring and interest in supporting research. Public and Patient Involvement and Engagement (PPIE) contacts from past research projects who were known to have the necessary skills and experience were contacted and given study information including a role descriptor to gauge interest. Informal discussions were held with the study team and perspective peer researchers could discuss the role with the study PPIE lead. Contracts were arranged for peer researchers’ paid involvement in the study as described in the ‘Recruitment of Participants’ section further above. Peer researchers attended an in-person training day, facilitated by the PI and PPIE lead. Content of the day included an in-depth discussion of their role, working together as peer researchers and how they wished to meet and support each other throughout data collection. Active listening skills were shared and practiced. A topic guide and checklist to guide monthly check ins was co-produced during and after the initial full training day with peer researchers, to facilitate consistent data capture while allowing flexibility to respond to participants’ individual circumstances. A companion reflexive guide was also developed to aid reflections and journaling after each check-in. Each peer researcher conducted monthly check-ins with five participants via telephone or Microsoft Teams. The post-doctoral research associate (PDRA) set up the meetings and attended the beginning of each meeting. This ensured that all could attend, hear and the conversation was recorded and saved directly to University of Surrey secure servers. Monthly conversations served multiple purposes: supporting participant engagement, providing opportunities to expand on survey responses, identifying experiences not captured through structured measures, and assessing the acceptability of peer-facilitated qualitative data collection over time. Peer researchers could contact the team via the PDRA at any point for urgent concerns and to obtain responses to participant questions at the monthly check-ins. Peer researchers met together quarterly over the duration of data collection (3 times at Months 3, 6, and 9) to reflect on their experiences as study companions and to provide feedback to the study team. These meetings supported integration of peer researchers experience and expertise into the wider study team activities. A final meeting post-data collection between the peer researchers and investigators (FS, CN, and RG) was an opportunity to collect overall feedback on peer researchers’ experiences during the project. Following the initial screening call with the PDRA, eligible participants who wanted to take part in the study were invited to provide their written informed consent and their availability for the study baseline visit. Fifteen unpaid carers were recruited, and baseline visits completed, during a 15-week period between February and May 2024 (eight participants completed the baseline visit in February, five in March-April, and two in May). Table 1 summarises the characteristics of the 15 carers who participated in the feasibility study. The sample was predominantly female and largely comprised individuals from White ethnic backgrounds, with representation from several minority ethnic groups. Most participants were middle-aged, with a smaller proportion of younger and older carers included. Educational attainment was generally high, with around two-thirds reporting higher education qualifications. Over half of the sample were married or cohabiting and a similar proportion were in paid employment, although a notable minority were either unable to work or not currently seeking employment. Prior caring experience was mixed, indicating variation in familiarity with caring roles among participants. In most cases, the person being cared for lived with the carer, while others supported individuals living independently or in supported accommodation. Overall, the sample reflects a diverse range of sociodemographic and caring contexts, supporting the feasibility of the mixed-methods data collection approach across varied carer circumstances. Recruitment took place between February and May 2024. All participants completed the baseline survey at enrolment and subsequently took part in the planned bi-weekly longitudinal surveys. In line with the study protocol, all data collection concluded in mid-December 2024. No participants formally withdrew from the study. However, three participants (20% of all participants) discontinued participation during the follow-up period due to the death of the person they were caring for. Overall, retention was high across the study period, with attrition attributable solely to bereavement rather than disengagement with the study procedures. Completion of the longitudinal surveys was high over the study period. Among the three participants who discontinued participation due to bereavement, completion ranged from one to four waves prior to discontinuation. The remaining twelve participants completed between nine and seventeen survey waves, reflecting variation in the timing of study entry. Overall, 189 longitudinal survey requests were issued, of which 176 were completed; 13 surveys were either not responded to or were initiated but not completed, yielding an overall completion rate of 93.12%. When restricted to participants who remained in the study until completion, 168 of 179 requested surveys were completed, corresponding to a completion rate of 93.85%. These findings indicate strong engagement with the longitudinal data collection procedures over an extended follow-up period. Overall, missing data was minimal, with an overall missingness rate of 0.7% across the study variables. The highest levels of missingness were observed for the two questions assessing the physical and mental burden associated with assisting the daily living activities of the care recipient, each with a missingness rate of 6.8%. In contrast, items assessing carers’ quality of life, depressive symptoms, sleep, and self-rated health exhibited very low levels of missingness (≤0.5%). We tested the feasibility of capturing acute “points of change” in carers’ circumstances over a four-month testing period. Overall, there were seven notifications received. Of these, two were deemed not to represent genuine points of change (e.g., reporting a grandchild’s holiday break), and two were submitted several days after the event had occurred. Three notifications were judged by the research team to constitute true points of change and triggered a five-day follow-up survey protocol. However, this approach proved challenging in practice. Participants frequently expressed uncertainty about what constituted a qualifying point of change, and the events of interest themselves often coincided with periods of heightened stress and disruption to daily routines. This contributed to delayed reporting and a lower completion rate for follow-up surveys (66.67%) compared with the routine fortnightly longitudinal surveys (93.12%). The research team additionally encountered operational challenges in administering follow-up surveys, including notifications occurring outside standard working hours (e.g., weekends). Given these feasibility and burden-related challenges, testing of the point-of-change survey component was suspended after four months. Monthly check-ins with the peer researchers commenced approximately 4 weeks after baseline and continued on a 4-weekly basis thereafter, where possible. One participant met with their peer researchers on a 6-weekly basis. The maximum number of check-ins during the active study period was ten, although the total number available varied depending on when participants joined the study. Completion rates were high, i.e., the frequency of the monthly meetings was maintained with the following exceptions: 5 participants missed a single check-in for carer-related reasons, 3 participants missed 1 or 2 check-ins for personal reasons, and 1 participant had a two-month gap between their second and third check-ins following bereavement. The third check-in has been at their request by way of follow-up with their peer researchers. Each check-in meeting was arranged for one hour, however, the duration of individual check-ins varied by carer, their caregiving responsibilities and life events more generally at any specific time. Some check-ins got shorter as the participant became more familiar with the survey and with little or no change in their circumstances to share. Whereas others took advantage of the full hour and used it to ‘offload’ with someone outside their usual support network. A total of 11 participants took part in the optional, post-study “exit interview” to provide their feedback on their study participation; specifically, in relation to data collection and the role of the peer researchers. Only participants who were still caring and providing study data in December were invited to take part in the exit interview. Feedback on the research and data collection approaches collected through monthly check-ins and the exit interview and survey are summarised below: Getting involved and commitment to the research Participants described a strong motivation for getting involved in the study, most commonly linked to an interest in research and a desire to contribute to improving understanding and support for unpaid carers. Many participants expressed a general belief in the value of research, with some noting prior involvement in PPIE or research activities and a sense that carers’ voices are often underrepresented. For several, the study “came at the right time,” offering an opportunity to reflect on their caring role during a particularly demanding period. Continued participation was often framed as a matter of personal commitment once enrolled, captured by sentiments such as “I’ve started, so I’ll finish.” While financial incentives were appreciated, participants consistently emphasised that these were not the primary motivator for engagement; instead, the perceived relevance of the research and the opportunity to be heard were central to sustained involvement. Accessibility Feedback indicated that the study was generally perceived as accessible and manageable alongside caring responsibilities. Participants valued the flexibility of participation, particularly the ability to complete surveys at a time that suited them and to engage in check-ins remotely. The digital survey format was described as straightforward and easy to navigate, even during periods of heightened stress. Clear communication from the research team and reminders were seen as supportive rather than burdensome. Some participants noted that carers with different levels of digital confidence or from underrepresented groups might experience greater barriers, suggesting that additional modes of access or tailored support could further enhance inclusivity. Overall, however, the approach was viewed as appropriately sensitive to the constraints faced by unpaid carers. Data collection approach Participants reflected positively on the overall balance between structured quantitative surveys and more open-ended opportunities to share experiences. The fortnightly surveys were consistently described as quick to complete, manageable alongside caring responsibilities, and broadly relevant to their lived experiences. Several participants noted that the regular survey schedule prompted reflection on aspects of wellbeing and caregiving that might otherwise go unnoticed, particularly during periods where routines became normalised despite ongoing strain. Importantly, participants valued the opportunity to contextualise and elaborate on survey responses during the monthly peer-researcher check-ins, especially when fixed-response items felt insufficient to capture the complexity or emotional texture of their experiences. The ability to explain why a response had changed, or why it had not, was seen as critical to making the data collection feel meaningful rather than mechanistic. During the first four months of the study, small iterative refinements were made to the survey content and wording in response to participant feedback. These changes, including clearer phrasing and the inclusion of additional free-text options, were welcomed and reinforced participants’ perceptions that the study was responsive to their input. As mentioned above, participants and researchers both identified challenges with the event-triggered “point of change” survey component. Participants reported uncertainty about what constituted a qualifying event, and periods in which meaningful changes occurred were frequently described as times of heightened stress and reduced capacity to engage with additional study tasks. This contributed to delayed reporting of events and lower completion of follow-up micro-surveys compared with routine fortnightly surveys. The monthly peer-researcher check-ins were consistently highlighted as a particularly valued component of the study. Participants emphasised the importance of continuity, with many expressing a strong preference for meeting with the same peer researcher each month in order to build rapport and trust. The shared lived experience of caring was seen as central to the success of the check-ins, enabling participants to speak openly without feeling the need to explain or justify their feelings. Participants described the check-ins as supportive, reflective, and distinct from formal services, with one noting that the companion “understood without me having to explain everything.” While the primary purpose was not therapeutic, participants often experienced the conversations as emotionally validating and helpful in making sense of their caring role. A small number reflected on the possibility that different personalities might not always align, but overall, the peer-researcher model was viewed as acceptable, appropriate, and integral to sustained engagement in the study. This study assessed the feasibility of a mixed-method longitudinal data collection approach designed to capture unpaid carers’ quality of life and lived experiences over time. Overall, the findings demonstrate that sustained, fortnightly digital survey data collection, when combined with regular peer-researcher check-ins, is both feasible and acceptable for unpaid carers across diverse caring contexts. High retention, strong survey completion rates, and minimal missing data over an extended follow-up period indicate that this approach can successfully support repeated data collection without imposing excessive burden. Our findings are consistent with prior research showing that intensive longitudinal methods (e.g. ecological momentary assessment) are generally feasible and acceptable for family caregivers.18 For example, a recent 15-day diary study of working dementia caregivers achieved a ~93% compliance rate and was rated as easy to use,19 underscoring that frequent digital data collection is possible when well-designed. Extending this evidence, the present study shows that surveys administered on a fortnightly basis can be sustained over a substantially longer period, approaching one year. A key methodological insight from this feasibility study concerns the relative strengths and limitations of different strategies for capturing change over time. Routine, predictable longitudinal surveys were consistently well-engaged with, suggesting that carers value data collection approaches that are low-burden, clearly structured, and easily incorporated into existing routines. Notably, caregivers in other intensive studies have preferred assessments timed to fit their daily schedules,19 which may explain the strong engagement we observed with regular fortnightly surveys. In contrast, the event-triggered “point of change” component proved difficult to operationalise in practice. Participants reported uncertainty about identifying qualifying events, and periods of acute change were often accompanied by heightened stress and reduced capacity to engage with additional survey requests. These findings suggest that participant-initiated, event-based data collection may not be well-aligned with the realities of unpaid caregiving over extended periods. The mixed-method design mitigated some of these limitations by allowing carers to retrospectively contextualise and interpret change during monthly peer-researcher check-ins. These conversations enabled participants to explain fluctuations, continuity, and turning points that were not easily captured through structured survey items alone. This approach leverages the complementary strengths of qualitative and quantitative methods: integrating open-ended, narrative data can enrich understanding of trends observed in survey responses.20 In our study, the qualitative insights provided a narrative backdrop for the quantitative scores, aiding in interpreting why a given carer’s well-being might have improved, declined, or remained stable. Such an explanatory mixed-methods strategy is consistent with broader evidence that combining surveys with interviews can enhance the depth and validity of longitudinal research findings.20 The check-in discussions, therefore, were not merely add-ons but a crucial interpretive layer, allowing the research team to capture the “why” and “how” behind the numbers over time. The peer-researcher model emerged as a central mechanism for sustaining engagement and enhancing the interpretability of longitudinal data. Because the check-ins were conducted by trained peer researchers with lived caregiving experience, a foundation of trust and mutual understanding was quickly established. Shared lived experience has been shown to facilitate rapport and comfort in qualitative research,21 and in our study it meant participants did not feel the need to constantly explain or justify their feelings and situations. This dynamic created a space for reflective sense-making that was distinct from both formal services and conventional research interviews. Unlike talking with healthcare professionals (which may carry fears of judgment or intervention) or with academic researchers (who may lack experiential understanding), talking with a peer allowed carers to open up with less reservation. The value of this approach resonates with previous literature on peer interviewing in hard-to-reach groups: involving insiders who share participants’ background can improve data quality and make participants more at ease during the research process.21 While not intended as a therapeutic intervention, the peer-facilitated check-ins were frequently described by participants as supportive and validating. This highlights a potential dual benefit of the peer-engagement model for both data quality and participant well-being. On one hand, having empathetic peers collect qualitative data likely enriched the information gathered. On the other hand, participants experienced the process as emotionally supportive. This finding is echoed by studies showing that engaging peer supporters or researchers can increase participants’ comfort and even confer psychosocial benefits.21,22 From a scalability perspective, these findings point to several considerations for future research. The peer-researcher model does introduce additional resource requirements (for recruitment, training, supervision, and compensation of peer staff ).21 In larger studies or trials, sustaining one-on-one peer check-ins at high frequency may be challenging. However, our results suggest that this investment may be offset by gains in participant retention and data completeness. Future work should explore how to adapt this approach for larger samples or broader implementation while preserving its core strengths. This might involve reducing the frequency of check-ins (e.g. quarterly instead of monthly in very large cohorts), leveraging group-based peer support sessions, or integrating more automated or remote communication tools to supplement peer interactions. In summary, this feasibility study demonstrates that a mixed-method longitudinal approach combining regular digital surveys with peer-researcher engagement is a promising and acceptable strategy for capturing unpaid carers’ experiences over time. The findings highlight the importance of predictability, relational support, and inclusiveness in research design, and provide practical insights to inform the development of future longitudinal studies seeking to balance methodological rigour with sensitivity to carers’ lived realities. The data generated in this study include high-frequency longitudinal survey responses combined with detailed qualitative information collected through monthly check-ins. Due to the richness, granularity, and longitudinal nature of these data, full anonymisation is not feasible without substantially compromising data integrity. In particular, the data contain potentially identifiable personal information and contextual details that could increase the risk of participant re-identification. For these reasons, the study data cannot be made publicly available. However, access to the data for secondary analysis may be considered on a case-by-case basis for requests with clearly defined, scientifically sound objectives that are consistent with the original ethical approvals and the informed consent provided by participants. Any approved data access will be subject to the completion of a formal data sharing agreement designed to protect participant confidentiality and privacy, including restrictions on data use, storage, and onward sharing. Requests for data access should be submitted to the corresponding author. All requests will be reviewed by the investigators of the study, and access will be granted only when the proposed use is judged to be ethically appropriate, methodologically robust, and compliant with data protection requirements. Extended data supporting this study are publicly available via the Open Science Framework (OSF) at https://osf.io/p2vuc. These materials include the study survey questionnaire, the monthly check-in topic guide, reflection guide, and checklist used during data collection. - 1. Spiers GF, Liddle J, Kunonga TP, et al.: What are the consequences of caring for older people and what interventions are effective for supporting unpaid carers? A rapid review of systematic reviews. BMJ Open. 2021 Sept 29; 11(9): e046187. PubMed Abstract | Publisher Full Text - 2. Carers UK: Unpaid care in England and Wales valued at £445 million per day.[cited 2026 Jan 6]. Reference Source - 3. Redican E, Meade R, Harrison C, et al.: The prevalence, characteristics, and psychological wellbeing of unpaid carers in the United Kingdom. Soc. Psychiatry Psychiatr. Epidemiol. 2025; 60(4): 869–879. PubMed Abstract | Publisher Full Text - 4. Runacres J, Herron D: Designing Inclusive Qualitative Research with Carers of People Living with Dementia: Methodological Insights. Healthcare (Basel). 2023 July 25; 11(15): 2125. Publisher Full Text - 5. Pennington BM, Alava MH, Strong M: Unpaid Caring and Health-Related Quality of Life: Longitudinal Analysis of Understanding Society (the UK Household Longitudinal Survey). Value Health. 2025 Jan 1; 28(1): 138–147. PubMed Abstract | Publisher Full Text - 6. Rand SE, Malley JN, Netten AP, et al.: Factor structure and construct validity of the Adult Social Care Outcomes Toolkit for Carers (ASCOT-Carer). Qual. Life Res. 2015 Nov; 24(11): 2601–2614. PubMed Abstract | Publisher Full Text - 7. Joseph S, Becker S, Elwick H, et al.: Adult carers quality of life questionnaire (AC-QoL): development of an evidence-based tool. Ment. Health Rev. J. 2012; 17(2): 57–69. - 8. NHS England Digital: Survey of Adult Carers in England.[cited 2026 Jan 6]. Reference Source - 9. Wilson E, Killick C, Harvey M, et al.: Young Onset Dementia – Peer Research: exploring the insights of Informal Carers. Practice. 2025 Oct 22 [cited 2026 Jan 6]: 1–15. Publisher Full Text Reference Source - 10. Ibáñez-Carrasco F, Watson JR, Tavares J: Supporting peer researchers: recommendations from our lived experience/expertise in community-based research in Canada. Harm Reduct. J. 2019 Sept 3; 16(1): 55. PubMed Abstract | Publisher Full Text - 11. Coughlin SS: Recall bias in epidemiologic studies. J. Clin. Epidemiol. 1990 Jan 1; 43(1): 87–91. PubMed Abstract | Publisher Full Text - 12. Daynes-Kearney R, Gallagher S: Online Support Groups for Family Caregivers: Scoping Review. J. Med. Internet Res. 2023 Dec 13; 25: e46858. Publisher Full Text - 13. Greenwood N, Habibi R, Mackenzie A, et al.: Peer support for carers: a qualitative investigation of the experiences of carers and peer volunteers. Am. J. Alzheimers Dis. Other Dement. 2013 Sept; 28(6): 617–626. PubMed Abstract | Publisher Full Text - 14. Candon D, Hewitt M, Liu-Smith Y, et al.: Do carer tasks predict carer employment? Evidence from the Survey of Adult Carers in England. Soc. Policy Adm. 2024 Jan; 58(1): 122–140. Publisher Full Text - 15. Kroenke K, Strine TW, Spitzer RL, et al.: The PHQ-8 as a measure of current depression in the general population. J. Affect. Disord. 2009; 114(1): 163–173. - 16. Giovannetti ER, Wolff JL, Frick KD, et al.: Construct Validity of the Work Productivity and Activity Impairment Questionnaire across Informal Caregivers of Chronically Ill Older Patients. Value Health. 2009 Sept; 12(6): 1011–1017. PubMed Abstract | Publisher Full Text - 17. Hart SG: Nasa-Task Load Index (NASA-TLX); 20 Years Later. Proceedings of the Human Factors and Ergonomics Society Annual Meeting. 2006 Oct; 50(9): 904–908. Publisher Full Text - 18. Han A, Malone LA, Lee HY, et al.: The use of ecological momentary assessment for family caregivers of adults with chronic conditions: A systematic review. Health Psychol. Res. 12: 93907. Publisher Full Text - 19. Chen S, Liu H, Lou VWQ: Monitoring daily well-being and meaning-making tendencies among adult child working dementia caregivers: validating an experience sampling study protocol. BMC Geriatr. 2022 Aug 29; 22: 714. Publisher Full Text - 20. Östlund U, Kidd L, Wengström Y, et al.: Combining qualitative and quantitative research within mixed method research designs: A methodological review. Int. J. Nurs. Stud. 2011 Mar; 48(3): 369–383. PubMed Abstract | Publisher Full Text - 21. Devotta K, Woodhall-Melnik J, Pedersen C, et al.: Enriching qualitative research by engaging peer interviewers: a case study. Qual. Res. 2016 Dec; 16(6): 661–680. Publisher Full Text - 22. Cui S, Crowe-Cumella H, Fortuna KL, et al.: A state-of-the-art narrative review of peer support for family caregivers of people with dementia: from in-person to digital delivery. Mhealth. 2024 Dec 15; 11: 9. Publisher Full Text Author details Author details 1 School of Health Sciences, University of Surrey Faculty of Health and Medical Sciences, Guildford, England, UK 2 School of Engineering and Informatics, University of Sussex, Brighton, England, UK 3 School of Computer Science and Electronic Engineering, University of Surrey Faculty of Engineering and Physical Sciences, Guildford, England, UK 4 School of Chemistry and Chemical Engineering, University of Surrey Faculty of Engineering and Physical Sciences, Guildford, England, UK 5 School of Biosciences, University of Surrey Faculty of Health and Medical Sciences, Guildford, England, UK 2 School of Engineering and Informatics, University of Sussex, Brighton, England, UK 3 School of Computer Science and Electronic Engineering, University of Surrey Faculty of Engineering and Physical Sciences, Guildford, England, UK 4 School of Chemistry and Chemical Engineering, University of Surrey Faculty of Engineering and Physical Sciences, Guildford, England, UK 5 School of Biosciences, University of Surrey Faculty of Health and Medical Sciences, Guildford, England, UK Haomiao Jin Roles: Conceptualization, Data Curation, Formal Analysis, Funding Acquisition, Investigation, Methodology, Resources, Software, Validation, Visualization, Writing – Original Draft Preparation Roles: Conceptualization, Data Curation, Formal Analysis, Funding Acquisition, Investigation, Methodology, Resources, Software, Validation, Visualization, Writing – Original Draft Preparation Richard Green Roles: Conceptualization, Funding Acquisition, Investigation, Methodology, Project Administration, Resources, Writing – Original Draft Preparation Roles: Conceptualization, Funding Acquisition, Investigation, Methodology, Project Administration, Resources, Writing – Original Draft Preparation Frances Sanders Roles: Data Curation, Formal Analysis, Investigation, Project Administration, Resources, Software, Validation, Visualization, Writing – Original Draft Preparation Roles: Data Curation, Formal Analysis, Investigation, Project Administration, Resources, Software, Validation, Visualization, Writing – Original Draft Preparation Alex Penn Roles: Conceptualization, Funding Acquisition, Investigation, Methodology, Resources, Writing – Review & Editing Roles: Conceptualization, Funding Acquisition, Investigation, Methodology, Resources, Writing – Review & Editing Sotiris Moschoyiannis Roles: Conceptualization, Funding Acquisition, Investigation, Project Administration, Resources, Supervision, Writing – Review & Editing Roles: Conceptualization, Funding Acquisition, Investigation, Project Administration, Resources, Supervision, Writing – Review & Editing Gustavo Carneiro Roles: Conceptualization, Funding Acquisition, Writing – Review & Editing Roles: Conceptualization, Funding Acquisition, Writing – Review & Editing Tao Chen Roles: Conceptualization, Funding Acquisition, Writing – Review & Editing Roles: Conceptualization, Funding Acquisition, Writing – Review & Editing Heather Gage Roles: Conceptualization, Funding Acquisition, Methodology, Writing – Review & Editing Roles: Conceptualization, Funding Acquisition, Methodology, Writing – Review & Editing Morro Touray Roles: Methodology, Writing – Review & Editing Roles: Methodology, Writing – Review & Editing Caroline Nicholson Roles: Conceptualization, Funding Acquisition, Investigation, Methodology, Project Administration, Resources, Supervision, Writing – Original Draft Preparation Roles: Conceptualization, Funding Acquisition, Investigation, Methodology, Project Administration, Resources, Supervision, Writing – Original Draft Preparation Competing interests No competing interests were disclosed. Grant information The author(s) declared that no grants were involved in supporting this work. Copyright © Crown copyright, 2026 Jin H et al.. This open access work is licensed under the Open Government Licence v3.0 metrics VIEWS $counts.viewCount downloads Citations CITE how to cite this article Jin H, Green R, Sanders F et al. The Care-Full Study: assessing the feasibility of a mixed-method longitudinal data collection approach for unpaid carers of people with multiple long-term conditions [version 1; peer review: 2 approved with reservations]. NIHR Open Res 2026, 6:14 (https://doi.org/10.3310/nihropenres.14229.1) NOTE: If applicable, it is important to ensure the information in square brackets after the title is included in all citations of this article. track receive updates on this article Track an article to receive email alerts on any updates to this article. Current Reviewer Status: ? Key to Reviewer Statuses VIEW HIDE ApprovedThe paper is scientifically sound in its current form and only minor, if any, improvements are suggested Approved with reservations A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit. Not approvedFundamental flaws in the paper seriously undermine the findings and conclusions Version 1 VERSION 1 PUBLISHED 16 Feb 2026 Views 0 How to cite this report: Towers AM and Lyons R. Reviewer Report For: The Care-Full Study: assessing the feasibility of a mixed-method longitudinal data collection approach for unpaid carers of people with multiple long-term conditions [version 1; peer review: 2 approved with reservations]. NIHR Open Res 2026, 6:14 (https://doi.org/10.3310/nihropenres.15493.r39634) The direct URL for this report is: https://openresearch.nihr.ac.uk/articles/6-14/v1#referee-response-39634 https://openresearch.nihr.ac.uk/articles/6-14/v1#referee-response-39634 NOTE: it is important to ensure the information in square brackets after the title is included in this citation. Reviewer Report 12 Mar 2026 Ruby Lyons, Alzheimer's Society (Ringgold ID: 4784), London, England, UK Approved with Reservations VIEWS 0 Summary Thank you for the opportunity to review this interesting paper, which highlights a rationale for a mixed methods methodology for data collection amongst unpaid carers. Previous data collection has been cross-sectional often only focusing on one or two ... Continue reading We confirm that we have read this submission and believe that we have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however we have significant reservations, as outlined above. Close Thank you for the opportunity to review this interesting paper, which highlights a rationale for a mixed methods methodology for data collection amongst unpaid carers. Previous data collection has been cross-sectional often only focusing on one or two ... Continue reading Summary Thank you for the opportunity to review this interesting paper, which highlights a rationale for a mixed methods methodology for data collection amongst unpaid carers. Previous data collection has been cross-sectional often only focusing on one or two points in time for data collection. Due to the changing and challenging nature of caring for someone with multiple long-term conditions, the researchers have suggested using a longitudinal data collection method comprising of fortnightly self-report surveys and monthly check-ins with a trained peer researcher with lived experience of caring, to measure and monitor the unexpected changes and emotional burdens of caring.

and rationale The paper clearly describes the limitations of cross-sectional methods of data collection and articulates the potential benefit of adopting a mixed-methods approach. The paper also highlights the involvement of those with lived experience in guiding the research and in formulating the mixed methods longitudinal data collection approach to suit those with demands on their time, money and emotional burden, as can happen with unpaid carers. The background section is well written. A minor point but given the PSS SACE is England-specific and the study sites are also all in England, perhaps ‘relevant within the English care system’ would be more accurate than “relevant within the UK care system.” A sentence and/or justification regarding terminology and use of the word carer would be welcome. Language is constantly evolving and recently some people in touch with the Alzheimer's Society have said they do not identify with the label of "carer," preferring instead "supporter."

The method is well written and mostly clear but would benefit from some additional information. For transparency, please confirm when participants joined the study. The text states that the “maximum number of check-ins during the active study period was ten, although the total number available varied depending on when participants joined the study”. We cannot see any additional information about this. It is important to be clear about how many months each participant was involved to contextualise the number of check-ins attended and overall retention period. Please also clarify exactly how many participants were eligible for the post-study exist interview (11 took part out of how many eligible participants?). Some detail about the selection and training of peer researchers is included but given the methodological importance placed on these individuals, the paper would benefit from more information about the peer researchers themselves, their characteristics and experience (including previous research training, given they were experienced in PPIE already). The argument for peer researchers, versus academic researchers, is that they were more able to build and maintain relationships because of their shared experience. It would therefore be useful to map the peer researchers’ characteristics and experiences to the five participants they supported. Perhaps this could be added to table one so that participants are clustered around each peer researcher, who is described there as well (e.g. age, gender identify, previous caring experience and whether the person they cared for lived with them etc). There is a lack of detail about how the qualitative check-ins were analysed and by whom. Replicability The recruitment process across the three sites is clear. The authors have described the survey questions and qualitative measures and OSF links are provided for closer examination. However, there are some gaps that should be addressed to allow replication. The use of peer researchers is a key component of this methodology. Readers would benefit from additional detail about these individuals and how they were trained. See points above. There is also a lack of information about how participants were assigned to peer researcher groups. Was it random or perhaps related to caring experience? Did the team consider gender, age, ethnicity when assigning to groups? Could participants state preferences regarding their peer researcher (e.g. same gender)? This could then be also picked up in the results and the discussion. What quality controls were put in place to ensure the rigor, objectivity and ethical practices of the peer researchers? How were they supported and how were check-in recordings analysed (and by whom)? Did you have a protocol for dealing with potential issues? What would you have done if a peer researcher had left the study and how might this be factored into future studies? Did any participants change peer researcher groups (and could they if they wanted to)? What are the implications for future research/considerations for others wanting to use this approach?

A strength of the paper is the participant characteristics, which are clear and descriptive. Another strength is the completion rates, which are crucial when assessing the feasibility of longitudinal research. However, related to the points made under method, it would be helpful to report months involved in the study (as not all were involved in the maximum 10-month period). Given high levels of digital exclusion amongst older carers, it would be useful to have a breakdown of the number of check-ins conducted online vs by telephone. It would also be helpful to report peer researcher experience and characteristics, ideally against participant characteristics, so that readers can better understand shared experiences. Feasibility extends not just to the participants in this case but also the use of peer researchers as a key part of the data collection. What support did they require from the research team, beyond the initial training? Were there any challenges for them (e.g. triggering memories and emotions from their own caring experiences)? Were there any issues raised between the participants and the peer researchers and, if so, how were they overcome?

and conclusion The Discussion is well written and thoughtful. The retention and completion rates are strong findings that support the conclusion that the approach is feasible and acceptable. These findings are also presented clearly and consistently throughout the paper. Contextualising quantitative data with qualitative data to understand the ‘why’ and the ‘how’ has been helpful in research with care home residents as well and could be cited to further strengthen this point.

on the selection, training, and ongoing support of the peer researchers is absent and would strengthen this section. Some discussion of the time required to build rapport enough for a carer to be open and share their experiences, without having met the person face to face, would be helpful. Reflection on digital exclusion and the importance of offering check-ins in different ways to support research inclusion (not just online) is currently missing. The Discussion would benefit from a separate Strengths and Limitations section, including: Thank you for the opportunity to review this interesting paper, which highlights a rationale for a mixed methods methodology for data collection amongst unpaid carers. Previous data collection has been cross-sectional often only focusing on one or two points in time for data collection. Due to the changing and challenging nature of caring for someone with multiple long-term conditions, the researchers have suggested using a longitudinal data collection method comprising of fortnightly self-report surveys and monthly check-ins with a trained peer researcher with lived experience of caring, to measure and monitor the unexpected changes and emotional burdens of caring.

and rationale The paper clearly describes the limitations of cross-sectional methods of data collection and articulates the potential benefit of adopting a mixed-methods approach. The paper also highlights the involvement of those with lived experience in guiding the research and in formulating the mixed methods longitudinal data collection approach to suit those with demands on their time, money and emotional burden, as can happen with unpaid carers. The background section is well written. A minor point but given the PSS SACE is England-specific and the study sites are also all in England, perhaps ‘relevant within the English care system’ would be more accurate than “relevant within the UK care system.” A sentence and/or justification regarding terminology and use of the word carer would be welcome. Language is constantly evolving and recently some people in touch with the Alzheimer's Society have said they do not identify with the label of "carer," preferring instead "supporter."

The method is well written and mostly clear but would benefit from some additional information. For transparency, please confirm when participants joined the study. The text states that the “maximum number of check-ins during the active study period was ten, although the total number available varied depending on when participants joined the study”. We cannot see any additional information about this. It is important to be clear about how many months each participant was involved to contextualise the number of check-ins attended and overall retention period. Please also clarify exactly how many participants were eligible for the post-study exist interview (11 took part out of how many eligible participants?). Some detail about the selection and training of peer researchers is included but given the methodological importance placed on these individuals, the paper would benefit from more information about the peer researchers themselves, their characteristics and experience (including previous research training, given they were experienced in PPIE already). The argument for peer researchers, versus academic researchers, is that they were more able to build and maintain relationships because of their shared experience. It would therefore be useful to map the peer researchers’ characteristics and experiences to the five participants they supported. Perhaps this could be added to table one so that participants are clustered around each peer researcher, who is described there as well (e.g. age, gender identify, previous caring experience and whether the person they cared for lived with them etc). There is a lack of detail about how the qualitative check-ins were analysed and by whom. Replicability The recruitment process across the three sites is clear. The authors have described the survey questions and qualitative measures and OSF links are provided for closer examination. However, there are some gaps that should be addressed to allow replication. The use of peer researchers is a key component of this methodology. Readers would benefit from additional detail about these individuals and how they were trained. See points above. There is also a lack of information about how participants were assigned to peer researcher groups. Was it random or perhaps related to caring experience? Did the team consider gender, age, ethnicity when assigning to groups? Could participants state preferences regarding their peer researcher (e.g. same gender)? This could then be also picked up in the results and the discussion. What quality controls were put in place to ensure the rigor, objectivity and ethical practices of the peer researchers? How were they supported and how were check-in recordings analysed (and by whom)? Did you have a protocol for dealing with potential issues? What would you have done if a peer researcher had left the study and how might this be factored into future studies? Did any participants change peer researcher groups (and could they if they wanted to)? What are the implications for future research/considerations for others wanting to use this approach?

A strength of the paper is the participant characteristics, which are clear and descriptive. Another strength is the completion rates, which are crucial when assessing the feasibility of longitudinal research. However, related to the points made under method, it would be helpful to report months involved in the study (as not all were involved in the maximum 10-month period). Given high levels of digital exclusion amongst older carers, it would be useful to have a breakdown of the number of check-ins conducted online vs by telephone. It would also be helpful to report peer researcher experience and characteristics, ideally against participant characteristics, so that readers can better understand shared experiences. Feasibility extends not just to the participants in this case but also the use of peer researchers as a key part of the data collection. What support did they require from the research team, beyond the initial training? Were there any challenges for them (e.g. triggering memories and emotions from their own caring experiences)? Were there any issues raised between the participants and the peer researchers and, if so, how were they overcome?

and conclusion The Discussion is well written and thoughtful. The retention and completion rates are strong findings that support the conclusion that the approach is feasible and acceptable. These findings are also presented clearly and consistently throughout the paper. Contextualising quantitative data with qualitative data to understand the ‘why’ and the ‘how’ has been helpful in research with care home residents as well and could be cited to further strengthen this point.

on the selection, training, and ongoing support of the peer researchers is absent and would strengthen this section. Some discussion of the time required to build rapport enough for a carer to be open and share their experiences, without having met the person face to face, would be helpful. Reflection on digital exclusion and the importance of offering check-ins in different ways to support research inclusion (not just online) is currently missing. The Discussion would benefit from a separate Strengths and Limitations section, including: - Participants had high levels education, were highly motivated and recruited via known PPIE networks. - Data collection via online/ digital self-report surveys would exclude a large number of older, less digitally literate unpaid carers. This is briefly mentioned within the Results (Accessibility section) but the conclusions of the paper do not reflect this enough as a limitation of the generalisability of the findings. - Criteria for what constituted a qualifying “point of change” event were not clearly defined, meaning participants judged this for themselves and this led to misunderstandings. This may have partly contributed to this element of the study being withdrawn. - Is the rationale for developing the new method (or application) clearly explained? Yes - Is the description of the method technically sound? Partly - Are sufficient details provided to allow replication of the method development and its use by others? Partly - If any results are presented, are all the source data underlying the results available to ensure full reproducibility? Partly - Are the conclusions about the method and its performance adequately supported by the findings presented in the article? Partly Competing Interests: No competing interests were disclosed. Reviewer Expertise: I am a Professor of Social Care Research at King's College London and have a particular interest in mixed-methods approaches, especially with under-represented groups. I conducted this review with Ruby Lyons who is a Dementia Advisor for the Alzheimer's Society in London and working on a project with King's College London colleagues to raise awareness of young onset dementia. CITE HOW TO CITE THIS REPORT Towers AM and Lyons R. Reviewer Report For: The Care-Full Study: assessing the feasibility of a mixed-method longitudinal data collection approach for unpaid carers of people with multiple long-term conditions [version 1; peer review: 2 approved with reservations]. NIHR Open Res 2026, 6:14 (https://doi.org/10.3310/nihropenres.15493.r39634) The direct URL for this report is: https://openresearch.nihr.ac.uk/articles/6-14/v1#referee-response-39634 https://openresearch.nihr.ac.uk/articles/6-14/v1#referee-response-39634 NOTE: it is important to ensure the information in square brackets after the title is included in all citations of this article. Views 0 How to cite this report: Gridley K and Willcox M. Reviewer Report For: The Care-Full Study: assessing the feasibility of a mixed-method longitudinal data collection approach for unpaid carers of people with multiple long-term conditions [version 1; peer review: 2 approved with reservations]. NIHR Open Res 2026, 6:14 (https://doi.org/10.3310/nihropenres.15493.r39641) The direct URL for this report is: https://openresearch.nihr.ac.uk/articles/6-14/v1#referee-response-39641 https://openresearch.nihr.ac.uk/articles/6-14/v1#referee-response-39641 NOTE: it is important to ensure the information in square brackets after the title is included in this citation. Reviewer Report 06 Mar 2026 Mandy Willcox, University of York Department of Social Policy and Social Work (Ringgold ID: 152546), York, England, UK Approved with Reservations VIEWS 0 Thank you for the opportunity to review this interesting paper. The paper reports a longitudinal mixed methods feasibility study of a data collection approach for unpaid carers including fortnightly quantitative self-report surveys with monthly qualitative check-ins conducted by peer researchers. ... Continue reading We confirm that we have read this submission and believe that we have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however we have significant reservations, as outlined above. Close Thank you for the opportunity to review this interesting paper. The paper reports a longitudinal mixed methods feasibility study of a data collection approach for unpaid carers including fortnightly quantitative self-report surveys with monthly qualitative check-ins conducted by peer researchers. It is a well written paper describing a novel mixed methods approach with extensive public involvement throughout. Some further clarity on areas of the method and feasibility testing would strengthen this paper and enhance the replicability of the method. Is the rationale for developing the new method clearly explained? The rationale for the study is clearly explained and the Plain English Summary very accessible. Is the description of the method technically sound? Further detail about how the qualitative data were managed and analysed would help to demonstrate rigour. This should be detailed in the methods section.

would help for ‘eco mapping exercise’ and ‘systems mapping workshop’. More information about the mode of baseline data collection is needed, it is referred to as online, a call and a visit. It is not clear whether these were options for participants and they all chose online or if online was the only option. Are sufficient details provided to allow replication of the method development and its use by others? A real strength of this method is the peer researchers’ role in the monthly check-in meetings. More detailed information about the support offered to the peer researchers and their role would add to the replicability of this method. It is not clear from the article whether, prior to the monthly check-ins, the peer researchers accessed the survey results for the carers they were meeting to inform the conversations at the check-in. These conversations were audio recorded - how was the data then analysed? Apart from the quarterly meetings and option to contact the post-doc researcher if necessary, were there any other safeguards or support mechanisms put in place to ensure the well-being or methodological rigour of the peer researchers? The authors discuss the variation in timing of study entry but do not expand on the reasons for this or what this meant in practice. The article states all data collection stopped in mid-December, so not all participants completed surveys for the full 10 months. How is this limitation factored into the results? What were the implications of dropping the event triggered survey, did the fortnightly surveys and monthly check-ins capture these key events? It would be useful to have some further clarity on the coaching sessions offered to the participants, when were these offered (during the study/after the study) and whether the authors had considered any implications of the use of this approach to promote engagement in future studies where QoL, health and well-being (i.e. things that could be influenced by coaching) may be outcomes measured in the study itself. If any results are presented, are all the source data underlying the results available to ensure full reproducibility? It would be interesting to know whether the reasons for the blank survey questions were explored in the optional interviews or at the check-ins. This would support the feasibility of the self-report survey completion. A section could be added to table 1. indicating duration of participation. A table with the completion rates for all 15 participants for both the surveys and check-ins would provide a clearer representation of these data alongside the narrative descriptions. This would help the reader to understand the implications of staggered entry and differences in the number of ‘waves’ of data collection each participant engaged in. Are the conclusions about the method and its performance adequately supported by the findings presented in the article? A separate section addressing the strengths and limitations of the study would improve this paper. In particular, authors could address the limited diversity of the participants, the self-selected nature of the sample and the implications this might have for a full trial or cohort study. Whilst the authors noted that participants came from a range of backgrounds and situations, they were reached through established networks and all actively opted into the study (responding to an advert by email) so are likely to be unusual in their motivation to take part (indeed, the authors state on page 11 ‘Participants described a strong motivation for getting involved in the study, most commonly linked to an interest in research…’). It is not possible to say from the evidence presented whether the longitudinal method tested would be as acceptable or have such high completion rates if participants were recruited more systematically from the wider carer population. In terms of strengths, the facility for participants to explain why a survey response was given or had changed at monthly check-ins was valued by participants and is a strength of the method that could add richness and meaning to future study findings using this method. The role of peer researchers was also a key strength, reportedly contributing to the high acceptability and perceived value of participation. However, from the article it is not clear whether this was independently assessed (i.e. by a researcher not involved in the check-ins, or through analysis of the audio recordings of check-ins?) Some further information about how acceptability and perceived value were assessed would be helpful. A final point relates more widely to the inevitable trade-off between independence and the development of trusting relationships in this approach. It was noted by the authors that the regular check-ins with an individual peer researcher with lived experience of caring established ‘a foundation of trust and mutual understanding’ which was instrumental in sustaining engagement with the research over time. A risk (as well as potential benefit for those taking part) here is that participants benefit therapeutically from this contact with peers which may influence the outcomes data collected. For some studies this may not be a problem (and could even give added value), but if the aim is to learn about the general experience and outcomes for participants of caring over time there may well be implications for generalisability, particularly in a landscape where such frequent, relevant and personalised contact is rarely available. Is the rationale for developing the new method clearly explained? The rationale for the study is clearly explained and the Plain English Summary very accessible. Is the description of the method technically sound? Further detail about how the qualitative data were managed and analysed would help to demonstrate rigour. This should be detailed in the methods section.

would help for ‘eco mapping exercise’ and ‘systems mapping workshop’. More information about the mode of baseline data collection is needed, it is referred to as online, a call and a visit. It is not clear whether these were options for participants and they all chose online or if online was the only option. Are sufficient details provided to allow replication of the method development and its use by others? A real strength of this method is the peer researchers’ role in the monthly check-in meetings. More detailed information about the support offered to the peer researchers and their role would add to the replicability of this method. It is not clear from the article whether, prior to the monthly check-ins, the peer researchers accessed the survey results for the carers they were meeting to inform the conversations at the check-in. These conversations were audio recorded - how was the data then analysed? Apart from the quarterly meetings and option to contact the post-doc researcher if necessary, were there any other safeguards or support mechanisms put in place to ensure the well-being or methodological rigour of the peer researchers? The authors discuss the variation in timing of study entry but do not expand on the reasons for this or what this meant in practice. The article states all data collection stopped in mid-December, so not all participants completed surveys for the full 10 months. How is this limitation factored into the results? What were the implications of dropping the event triggered survey, did the fortnightly surveys and monthly check-ins capture these key events? It would be useful to have some further clarity on the coaching sessions offered to the participants, when were these offered (during the study/after the study) and whether the authors had considered any implications of the use of this approach to promote engagement in future studies where QoL, health and well-being (i.e. things that could be influenced by coaching) may be outcomes measured in the study itself. If any results are presented, are all the source data underlying the results available to ensure full reproducibility? It would be interesting to know whether the reasons for the blank survey questions were explored in the optional interviews or at the check-ins. This would support the feasibility of the self-report survey completion. A section could be added to table 1. indicating duration of participation. A table with the completion rates for all 15 participants for both the surveys and check-ins would provide a clearer representation of these data alongside the narrative descriptions. This would help the reader to understand the implications of staggered entry and differences in the number of ‘waves’ of data collection each participant engaged in. Are the conclusions about the method and its performance adequately supported by the findings presented in the article? A separate section addressing the strengths and limitations of the study would improve this paper. In particular, authors could address the limited diversity of the participants, the self-selected nature of the sample and the implications this might have for a full trial or cohort study. Whilst the authors noted that participants came from a range of backgrounds and situations, they were reached through established networks and all actively opted into the study (responding to an advert by email) so are likely to be unusual in their motivation to take part (indeed, the authors state on page 11 ‘Participants described a strong motivation for getting involved in the study, most commonly linked to an interest in research…’). It is not possible to say from the evidence presented whether the longitudinal method tested would be as acceptable or have such high completion rates if participants were recruited more systematically from the wider carer population. In terms of strengths, the facility for participants to explain why a survey response was given or had changed at monthly check-ins was valued by participants and is a strength of the method that could add richness and meaning to future study findings using this method. The role of peer researchers was also a key strength, reportedly contributing to the high acceptability and perceived value of participation. However, from the article it is not clear whether this was independently assessed (i.e. by a researcher not involved in the check-ins, or through analysis of the audio recordings of check-ins?) Some further information about how acceptability and perceived value were assessed would be helpful. A final point relates more widely to the inevitable trade-off between independence and the development of trusting relationships in this approach. It was noted by the authors that the regular check-ins with an individual peer researcher with lived experience of caring established ‘a foundation of trust and mutual understanding’ which was instrumental in sustaining engagement with the research over time. A risk (as well as potential benefit for those taking part) here is that participants benefit therapeutically from this contact with peers which may influence the outcomes data collected. For some studies this may not be a problem (and could even give added value), but if the aim is to learn about the general experience and outcomes for participants of caring over time there may well be implications for generalisability, particularly in a landscape where such frequent, relevant and personalised contact is rarely available. - Is the rationale for developing the new method (or application) clearly explained? Yes - Is the description of the method technically sound? Yes - Are sufficient details provided to allow replication of the method development and its use by others? Partly - If any results are presented, are all the source data underlying the results available to ensure full reproducibility? No - Are the conclusions about the method and its performance adequately supported by the findings presented in the article? Partly Competing Interests: No competing interests were disclosed. Reviewer Expertise: I am a social care and dementia researcher with almost 20 years of experience of qualitative and mixed methods research and a particular interest in exploring new approaches to quantitative data collection. I supported an early career researcher to review this paper - she has a PhD in psychology and education/learning disability and currently works as a Research Associate on an NIHR funded feasibility study. CITE HOW TO CITE THIS REPORT Gridley K and Willcox M. Reviewer Report For: The Care-Full Study: assessing the feasibility of a mixed-method longitudinal data collection approach for unpaid carers of people with multiple long-term conditions [version 1; peer review: 2 approved with reservations]. NIHR Open Res 2026, 6:14 (https://doi.org/10.3310/nihropenres.15493.r39641) The direct URL for this report is: https://openresearch.nihr.ac.uk/articles/6-14/v1#referee-response-39641 https://openresearch.nihr.ac.uk/articles/6-14/v1#referee-response-39641 NOTE: it is important to ensure the information in square brackets after the title is included in all citations of this article. Alongside their report, reviewers assign a status to the article: - Approved - Approved with reservations - Not approved | Invited Reviewers | || |---|---|---| | 1 | 2 | | | Version 1 16 Feb 26 | read | read | Sign up for content alerts You are now signed up to receive this alert Alongside their report, reviewers assign a status to the article: Approved - the paper is scientifically sound in its current form and only minor, if any, improvements are suggested Approved with reservations - A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit. Not approved - fundamental flaws in the paper seriously undermine the findings and conclusions Provide sufficient details of any financial or non-financial competing interests to enable users to assess whether your comments might lead a reasonable person to question your impartiality. 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