Balancing adaptive delivery and implementation fidelity over time: a longitudinal mixed-methods study of a community health worker–led adolescent nutrition intervention in Uganda

Balancing adaptive delivery and implementation fidelity over time: a longitudinal mixed-methods study of a community health worker–led adolescent nutrition intervention in Uganda | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Balancing adaptive delivery and implementation fidelity over time: a longitudinal mixed-methods study of a community health worker–led adolescent nutrition intervention in Uganda Thomas Buyinza, Edward Buzigi, Shuyan Liu, Justine Bukenya, Mary Mwanyika Sando, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9602420/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract Background Adolescents and young adults (AYAs) aged 10–24 years in sub-Saharan Africa, including Uganda, experience poor diet quality and low nutrition literacy. Community health worker (CHW)–led interventions offer a promising delivery platform, yet little is known about how implementation unfolds under routine conditions or how adaptive delivery and fidelity interact. This gap limits the design and scale-up of community-based interventions without compromising core components. However, few studies have empirically examined how fidelity monitoring can inform bounded adaptations during implementation. We examined how adaptive delivery and implementation fidelity interacted over time during the nine-month implementation of a CHW-led intervention in Uganda. Methods This longitudinal mixed-methods implementation study was nested within a nine-month randomized controlled trial of a CHW-led adolescent nutrition education intervention in rural Eastern Uganda. Fidelity assessment was based on Carroll’s framework, and data were collected prospectively during routine delivery across three implementation periods: early, mid, and late. Qualitative data were collected through repeated focus group discussions with CHWs, adolescents, and parents during implementation. Data were analyzed using a hybrid inductive–deductive approach, with adaptive delivery processes identified inductively and organized using the Consolidated Framework for Implementation Research. Quantitative and qualitative data were integrated to examine how adaptive delivery and implementation fidelity interacted over time. Results Implementation fidelity varied across the nine-month implementation period, with higher levels during mid-implementation and lower levels in early and late periods. Five adaptive delivery processes were identified: negotiating flexible scheduling and revisits; reinforcing and contextualizing complex content to improve comprehension; tailoring dietary counselling to household constraints; applying micro-scheduling to sustain coverage; and leveraging household and community networks for continuity. Fidelity observations and implementation challenges informed supervisory reflection, guiding bounded adaptations in delivery while preserving core intervention components. Conclusion Adaptive delivery and implementation fidelity were dynamically interrelated during the nine-month delivery of the CHW-led adolescent nutrition education intervention under routine conditions. These processes unfolded through continuous reflection and adjustment in response to contextual influences. The findings indicate that adaptive delivery and implementation fidelity are best conceptualized as interdependent implementation processes, with supervision-mediated feedback supporting context-responsive adaptations while maintaining core intervention functions. Adaptive delivery implementation fidelity community health workers adolescent nutrition Consolidated Framework for Implementation Research implementation research rural Uganda Figures Figure 1 Figure 2 Contributions to the Literature Provides longitudinal empirical evidence on how adaptive delivery and implementation fidelity are interrelated during routine delivery of a community health worker–led intervention. Conceptualizes a supervision-mediated adaptation–fidelity feedback loop linking fidelity monitoring, reflective problem-solving, and bounded delivery adaptations. Demonstrates an analytic approach for integrating prospective fidelity assessment with repeated qualitative data on adaptive delivery processes in low-resource community health systems. Background Adolescents and young adults (AYAs) have increased nutritional requirements during a critical period of physical, cognitive, and psychosocial development [ 1 ]. However, unhealthy and inadequate dietary patterns remain widespread globally, particularly in Sub-Saharan Africa (SSA), where structural constraints limit access to healthy foods [ 2 – 6 ]. In Uganda, inadequate fruit and vegetable intake and low dietary diversity are common among AYAs [ 7 , 8 ]. These patterns are shaped by low nutrition literacy and broader socio-ecological influences, underscoring the need for contextually appropriate, household-level interventions that engage adolescents alongside their caregivers [ 9 – 12 ]. Community health workers (CHWs) play a central role in preventive health delivery in low- and middle-income countries, including Uganda, where they provide health education, counselling, and linkage to services at the household level [ 13 – 16 ]. In Uganda, CHWs ‒ commonly referred to as village health teams ‒ are lay community-based volunteers within the national health system [ 17 ] and are well positioned to reach adolescents, including those out of school. To address challenges in delivering adolescent-focused interventions through routine systems, a community-based adolescent nutrition education intervention was implemented through CHW platforms in Uganda as part of the ARISE-NUTRINT study [ 18 , 19 ]. While embedding interventions within CHW systems enhances feasibility and sustainability [ 17 , 20 ], it also exposes delivery to contextual constraints and changing community conditions that shape how interventions are implemented in practice [ 13 , 21 ]. Effective implementation depends not only on intervention design but also on how interventions are delivered within complex, resource-constrained health systems [ 20 , 22 , 23 ]. CHW-led programs often face contextual challenges, including competing livelihood demands, variability in implementer capacity and motivation, sociocultural norms, seasonal disruptions, and limited supervision [ 22 , 24 , 25 ]. These factors shape how interventions are delivered in practice, often requiring implementers to adjust delivery processes to sustain implementation. While such adjustments may improve contextual fit, unguided changes ‒particularly those affecting core intervention components ‒ may compromise fidelity. At the same time, adaptations to delivery forms may be necessary to sustain implementation in real-world settings [ 26 – 28 ]. Implementation fidelity, defined as the extent to which an intervention is delivered as intended, is critical for interpreting effectiveness [ 29 ]. However, fidelity may vary as implementation conditions change and implementers respond to emerging challenges, creating tension between maintaining adherence to core components and allowing flexibility in delivery. This is particularly important because fidelity and adaptation are often treated as competing priorities, yet implementation theory suggests that adaptations can support fidelity when they preserve core functions while modifying delivery forms [ 27 , 28 ]. Despite increasing recognition of this interplay, much of the adolescent nutrition literature in SSA has focused on intervention effectiveness, with limited attention to how delivery is adjusted in practice, how such adjustments are guided, and how adaptation and fidelity interact during routine implementation [ 30 – 35 ]. Implementation research has also often assessed determinants or fidelity at single time points, providing limited insight into how these processes evolve over time [ 36 , 37 ]. Empirical evidence on how this balance is actively managed during implementation remains limited, especially in CHW-led interventions in low-resource settings. Understanding these dynamics is important for informing implementation design and scale-up of community-based interventions within routine health systems. This study examined how adaptive delivery and implementation fidelity interacted over time during the nine-month implementation of the CHW-led intervention in rural Uganda. Methodology Study setting The study was conducted in rural Mayuge District within the Iganga–Mayuge Health and Demographic Surveillance Site (HDSS) in Eastern Uganda [ 38 ]. This setting is predominantly rural and characterized by subsistence farming, seasonal livelihood activities, and limited dietary diversity among adolescents [ 8 ]. Households in this context often experience fluctuations in food availability and access due to agricultural cycles and economic constraints, which shape dietary behaviours [ 11 ]. Study design This was a longitudinal mixed-methods implementation study nested within a nine-month randomized controlled trial of a CHW–led adolescent nutrition education intervention, delivered from 15 May 2025 to 16 January 2026. The study combined prospective quantitative fidelity observations with repeated qualitative data collection to examine adaptive delivery processes and contextual influences across early (months 1–3), mid (months 4–6), and late (months 7–9) implementation. This design enabled examination of how adaptive delivery processes and implementation fidelity evolved over time under routine conditions. Overview of the intervention and implementation strategies Details of the intervention and implementation strategies are reported elsewhere [ 19 ]. Briefly, this was a community-based adolescent nutrition education intervention delivered by CHWs to adolescents and their caregivers at the household level. The intervention comprised nine sequential monthly modules covering balanced diet, essential vitamins and minerals, reduction of sugar-sweetened beverages, correction of food-related myths, and prevention of anaemia. Each module was delivered during a structured household session using a visual-aided flyer. Sessions followed a standardized flow guided by standard operating procedures (SOPs), incorporating explanation of key messages, participatory discussion, and caregiver engagement to support household-level application. Sessions lasted approximately 40–50 minutes, and flyers were left with households for ongoing reference. For this study, core intervention functions were predefined as delivery of the nine modules, engagement of the adolescent, use of visual-aided counselling, caregiver involvement, and reinforcement of key nutrition messages. Adaptable delivery forms included visit timing, sequencing of revisits, communication approaches, locally feasible food substitutions, and follow-up arrangements. Core components were maintained to support fidelity, while allowing flexibility in delivery frequency and scheduling to accommodate contextual constraints. The main implementation strategies examined included SOP-guided delivery, supportive supervision, fidelity monitoring, feedback/debrief meetings, and guided problem-solving. Throughout implementation, CHWs received supportive supervision through observation of selected sessions using fidelity checklists and monthly debrief meetings. Supervisors reviewed delivery progress, discussed challenges, and guided context-appropriate adjustments while maintaining core components. Supportive supervision was treated as the central strategy through which fidelity observations and delivery challenges informed bounded adaptations. Study population and sampling The study population comprised three categories of respondents, including individuals who delivered or experienced the intervention: the implementers of the intervention (CHWs), intervention recipients (AYAs), and household influencers (parents of participating AYAs). Purposive sampling was used, guided by participants’ roles in implementation, level of exposure to the intervention, and ability to provide in-depth insights into implementation processes. All ten CHWs who implemented the intervention were included, and all consented to participate. For this intervention, CHWs received structured training on the use of visual-aided materials, facilitation of participatory discussions, and adherence to standard operating procedures. Their dual role as community members and implementers positioned them to take on supervised adaptive delivery strategies, in response to contextual challenges. AYA and parent/guardian participants were recruited at selected time points across early, mid, and late implementation to capture variation in age, sex, schooling status, and caregiving context. AYAs were grouped into three age categories (10–14, 15–19, and 20–24 years) to reflect developmental differences and ensure equal inclusion of both in-school and out-of-school participants. Across the study, 14 focus group discussions (FGDs) were conducted: six with CHWs, six with AYAs, and two with parents or guardians. The FGDs for CHWs followed a panel design involving the same ten participants across repeated rounds, to enable assessment of implementation learning over time. The FGDs for AYAs and parents involved different participants at selected time points to capture diverse recipient experiences across implementation periods while reducing repeated-participation burden. Each FGD included 8–10 participants, and 60 unique participants contributed to the qualitative component. Sampling and data collection proceeded iteratively until sufficient depth and variation in perspectives were achieved across participant groups. Conceptual framework We synthesized and framed an adaptation–fidelity feedback framework, drawing on the Consolidated Framework for Implementation Research (CFIR) [ 39 ], and Carroll’s fidelity framework [ 29 ], to guide this study. The framework assumes that fidelity monitoring identifies delivery challenges, supervision creates a space for reflection and problem-solving, and agreed delivery adaptations are then applied and reflected in subsequent fidelity patterns. Contextual influences, organized using the CFIR, are conceptualized as the conditions within which implementation occurs, including factors related to the outer setting, inner setting, intervention characteristics, characteristics of individuals, and implementation processes (Fig. 1 ). In this framework, implementation is conceptualized as a dynamic process in which contextual influences shape fidelity challenges, supervision mediates reflection and problem-solving, and bounded adaptations influence subsequent fidelity patterns, creating an iterative feedback loop over time. Within this framework, intervention delivery is understood as responsive to contextual conditions, with adjustments in delivery processes occurring during implementation. Implementation fidelity assessment draws on Carroll et al.’s framework, which defines fidelity across adherence, dose delivered, quality of delivery, participant responsiveness, and program differentiation. Adaptive implementation and fidelity are viewed as dynamically interrelated processes, with adaptations focused on delivery forms while preserving core intervention functions. Implementation experiences, including observed delivery challenges and fidelity patterns, inform reflection and problem-solving through supportive implementation processes, which in turn shape subsequent delivery adjustments. These adjustments are expected to influence later fidelity dimensions, creating an ongoing feedback process through which bounded adaptation evolved alongside implementation fidelity patterns over time under routine conditions. Data collection procedures Implementation fidelity Implementation fidelity data were collected prospectively during routine intervention delivery from June 2025 to January 2026, covering the full nine-month implementation period. Fidelity monitoring was conducted during supervisory field visits. Each of the ten CHWs was directly observed once in each of the three implementation periods (months 1–3, 4–6, and 7–9) during real-time intervention delivery sessions, resulting in three observations per CHW. This enabled assessment of variation in fidelity across implementation periods under routine delivery conditions. Fidelity was assessed using a structured observation checklist ( Supplementary Material 1 ) aligned with the five components of Carroll et al.’s framework: adherence, dose delivered, quality of delivery, participant responsiveness, and program differentiation [ 29 ]. Each component was measured using multiple items rated on a 5-point Likert scale (1 = strongly disagree, 2 = disagree, 3 = neutral, 4 = agree, and 5 = strongly agree), based on predefined scoring criteria. Scores were summarized descriptively to compare relative fidelity levels across implementation periods, rather than to test for statistical significance. Fidelity assessments were conducted by a trained field implementation supervisor during routine, unannounced visits and were recorded contemporaneously. Supervision included observation of delivery and structured reflection and feedback discussions based on observed implementation challenges. Post-observation discussions focused on identifying operational challenges and providing guidance on delivery practices. Adaptive delivery processes Qualitative data were collected to assess adaptive delivery processes and how delivery adjustments related to core intervention components during ongoing intervention delivery. Six FGDs were conducted with the ten CHWs after the first, second, third, fourth, fifth, and seventh implementation months. To capture perspectives of intervention recipients and households, six FGDs were conducted with AYAs and two with parents or guardians, with different participants engaged across rounds. Parent FGDs were conducted in the third and sixth months. Among AYAs, FGDs with those aged 10–14 and 15–19 years were conducted in the second month, those aged 20–24 and 10–14 years in the fourth month, and those aged 15–19 and 20–24 years in the seventh month. Different AYA age groups were purposively engaged at different time points to capture variation across developmental stages and implementation periods while minimizing repeat participation. All FGDs were guided by semi-structured discussion guides informed by the CFIR (Supplementary Material 2) and conducted in Lusoga by a trained three-member research team experienced in qualitative data collection. Each session was audio-recorded with informed consent and lasted between 60 and 90 minutes. Discussions were held in private community venues at times convenient to participants. Moderators were independent of program implementation. Although CHWs and local leaders supported participant recruitment and scheduling, they did not attend discussions. All audio recordings were transcribed verbatim in Lusoga and translated into English. Translations were cross-checked by team members fluent in both languages, and transcripts were pseudonymized and de-identified prior to analysis. Data management and analysis Implementation fidelity Quantitative fidelity data were entered, cleaned, and analyzed using Stata version 17.0. Composite fidelity scores were calculated by summing the five component scores (range 5–25). Scores were categorized as high (21–25), moderate (16–20), or low (≤ 15). Descriptive statistics (means, frequencies, and percentages) were used to summarize fidelity across implementation periods. Component-level analyses were conducted to describe performance across fidelity domains. Adaptive delivery processes All audio-recorded discussions were transcribed verbatim in Lusoga and translated into English by trained members of the research team and cross-checked by another team member. To ensure translation accuracy, an additional researcher independently reviewed selected transcripts against the original audio recordings. Transcripts were anonymized through removal of personal identifiers and assignment of pseudonyms. The transcripts were analyzed using NVivo version 12. Analysis followed a hybrid deductive–inductive thematic approach, informed by Braun and Clarke’s phases of thematic analysis [ 40 ]. The analysis focused on adaptive delivery processes, delivery forms modified, and whether core intervention components were maintained, with the CFIR used to organize these processes. Three researchers independently read all transcripts multiple times to achieve data immersion and developed initial analytic memos. This informed development of an initial codebook, which was iteratively refined through team discussions. Open coding was first applied to identify patterns in delivery processes. Subsequently, CFIR domains were used to organize adaptive delivery processes across intervention characteristics, outer setting, inner setting, characteristics of individuals, and implementation process domains. Each transcript was coded independently by at least two research team members. Coding discrepancies were resolved through consensus discussions involving all three analysts, with reference to analytic memos and original transcripts where necessary. Codes were grouped into subthemes and examined across implementation periods to describe variation over time. An audit trail comprising codebooks, analytic memos, and consensus records was maintained. All de-identified data were stored on password-protected servers. To integrate quantitative and qualitative findings, fidelity results from early, mid, and late implementation were interpreted alongside qualitative accounts of adaptive delivery processes collected during corresponding implementation periods. Integration focused on how fidelity patterns, delivery challenges, supervisory reflection, and adaptive responses interacted over time. Results Socio-demographic characteristics of participants Results are presented in four parts: participant characteristics, fidelity patterns over time, adaptive delivery processes, and integrated evidence on how supervision-guided adaptations aligned with fidelity patterns across implementation. A total of 60 participants were included: 30 AYAs, 20 parents or guardians, and 10 CHWs (Table 1 ). Most AYAs (28/30) had attained primary or secondary education. All CHWs were aged 25 years and above and had at least primary education. Parents were predominantly married or cohabiting. Across participant groups, most individuals resided in households of 5–10 members (n = 38). Table 1 Socio-demographic characteristics of participants (n = 60) Characteristic AYAs n = 30 Parents/Guardians n = 20 CHWs n = 10 Overall n = 60 Age Group 10–14 years 10 0 0 10 15–19 years 12 0 0 12 20–24 years 8 0 0 8 25 years and above 0 20 10 30 Schooling status (AYAs only) In-school 15 15 Out of school 15 15 Highest education attained Primary and below 16 12 1 29 Secondary 12 6 8 26 Tertiary 2 2 1 5 Household size 10 people 2 4 1 7 Marital status Single/never married 28 0 0 28 Married or cohabiting 2 16 10 28 Separated/Divorced 0 4 0 4 Disability Yes 2 0 0 2 No 28 20 10 58 Employment Formal 0 2 0 2 Informal 5 18 10 33 Not working 25 0 0 25 Implementation fidelity across the nine-month implementation period Implementation fidelity varied over the nine-month implementation period (Table 2 ). During months 1–3, two of the 10 CHWs were categorized as having high implementation fidelity, six as moderate, and two as low. During months 4–6, six CHWs were categorized as implementing with high fidelity, and none were classified as having low fidelity. By months 7–9, four CHWs were categorized as implementing with high fidelity, and three were classified as having low fidelity. Overall, fidelity was highest during the mid-implementation period, with low, moderate, and high-fidelity levels observed in the late period. Table 2 Overall implementation fidelity levels over time Fidelity level Months 1–3 (early) n (%) Months 4–6 (mid) n (%) Months 7–9 (late) n (%) Overall n (%) High fidelity (21–25) 2 (20.0) 6 (60.0) 4 (40.0) 12 (40.0) Moderate fidelity (16–20) 6 (60.0) 4 (40.0) 3 (30.0) 13 (43.3) Low fidelity (≤ 15) 2 (20.0) 0 (0.0) 3 (30.0) 5 (16.7) Total assessments 10 (100) 10 (100) 10 (100) 30 (100) Components of fidelity across the implementation period Component-level analysis showed variation in fidelity domains over time (Fig. 2 ). During early implementation, adherence averaged 3.6 (SD 0.7), increasing to 4.3 (SD 0.5) during the mid-implementation phase, and then decreasing slightly to 3.9 (SD 0.6) during the late phase. Similar patterns were observed for dose delivered (3.4, 4.2, 3.7) and participant responsiveness (3.2, 4.0, 3.4). Quality of delivery increased from 3.7 (SD 0.6) in early implementation to 4.4 (SD 0.5) in the mid-implementation phase and remained relatively high during the late phase (4.1, SD 0.6). Program differentiation remained consistently high across the implementation period (4.2, 4.5, 4.4). Overall, fidelity component scores were highest during the mid-implementation phase. Adaptive delivery processes and preservation of core intervention components Five themes were identified, reflecting adaptive delivery processes across the nine-month implementation period: flexible scheduling and revisits; contextualized reinforcement of complex content; resource-sensitive counselling adaptation; workload-responsive micro-planning; and network-supported participant follow-up (Table 3 ). Adaptive delivery involved modifications to delivery forms while maintaining core intervention components and was shaped through structured supervisory discussions that reviewed delivery experiences, identified emerging challenges, and guided context-appropriate adjustments. Observed delivery challenges and fidelity patterns informed supervisory reflection, which in turn shaped subsequent delivery practices. Across implementation, adaptations were bounded to preserve core intervention functions while allowing flexibility in delivery. These adaptive processes evolved alongside changes in fidelity dimensions, including adherence, quality of delivery, and participant responsiveness, indicating a dynamic feedback process over time. Table 3 Adaptive delivery processes, delivery forms modified, and core components protected Themes (adaptive delivery process) Description of the adaptation Delivery form modified Core component protected Outer setting : Flexible scheduling and revisits Adjusting home visit timing, conducting revisits, and coordinating with participants to address availability constraints due to schooling, livelihood activities, and mobility Visit timing, revisits, participant follow-up arrangements Completion of monthly module exposure and target adolescent engagement Intervention and individual characteristics : Contextualized reinforcement of complex content Reinforcing key messages through repetition and use of locally relevant examples to improve comprehension of complex intervention concepts Communication approach, examples used, repetition of explanations Key nutrition messages, visual-aided counselling, and participant comprehension Outer setting : Resource-sensitive counselling adaptation Aligning dietary recommendations with locally available and affordable foods while maintaining core intervention intent Locally feasible food examples and substitutions Core dietary messages on diversity, healthier choices, and anaemia prevention Inner setting and implementation process : Workload-responsive micro-planning Clustering household visits and adjusting schedules to manage competing CHW responsibilities and sustain delivery continuity CHW visit scheduling, clustering of nearby households, delivery sequencing Intervention dose, continuity of delivery, and SOP-guided session structure Outer and inner setting : Network-supported participant follow-up Engaging caregivers, neighbours, and local leaders to support participant follow-up and continuity of intervention exposure Follow-up pathways, caregiver/community contact mechanisms Participant retention, caregiver involvement, and continuity of exposure Outer setting: Flexible scheduling and revisit mechanisms In early implementation, participant availability constrained delivery, but by mid-implementation, CHWs increasingly applied structured rescheduling strategies, with further refinement observed in later months. Participant availability was shaped by livelihood activities, school attendance, and temporary mobility, which constrained the ability of CHWs to conduct household sessions as planned. During the first implementation month (May 2025), rainfall and agricultural labour demands disrupted planned visits and reduced daytime household availability, limiting opportunities for delivery. “Sometimes it rains when we are already on the way to deliver the education message to the households, so we fail to implement that day.” (CHW, male, 32 years, first implementation month) Parents also described how livelihood activities limited their availability during the day, requiring CHWs to adjust visit timing. “Sometimes during the day, we are not at home because we go to the farm or to work, so when they [CHWs] come and miss us, they have to return later.” (Parent, female, 41 years, third implementation month) Relatedly, adolescents also noted that their availability, particularly due to schooling, influenced scheduling of visits. “Sometimes I am at school or away, so they tell my parent they will come back when I am around.” (Adolescent, female, 14 years, fourth implementation month) In response to these challenges, CHWs adjusted by returning later in the day or rescheduling visits to subsequent days to ensure sessions were completed. Missed visits and incomplete sessions were reviewed during supervision, which guided refinement of scheduling approaches across CHWs. CHWs also addressed temporary relocation by coordinating with caregivers and community members to support follow-up, thereby maintaining continuity of module delivery while modifying visit timing and revisit patterns. “If we reach and find they have gone to the garden, we return in the evening or come back the next day so that we find them at home.” (CHW, female, 49 years, fourth implementation month) Intervention and individual characteristics: Contextualized reinforcement of complex content Initial challenges in explaining certain concepts during early implementation gave way to more effective, contextualized communication approaches during mid and late implementation. Some intervention topics were initially difficult for adolescents and their parents to understand, particularly those perceived as abstract or not directly observable in daily life. CHWs described initial difficulties in explaining certain topics, particularly where adolescents could not easily relate them to everyday experiences. “Training on anaemia was hard at first because the adolescents did not know that poor diet quality and worms can make them have little blood in their bodies.” (CHW, male, 56 years, first implementation month) Both CHWs and the intervention recipients (adolescents and parents) described initial difficulties in understanding some nutrition concepts before repeated explanation. “At first I did not understand some of the lessons even though they were in Lusoga language, but when they kept explaining and using examples we see at home, I started to understand.” (Young adult, female, 20 years, third implementation month) “When they explain slowly and repeat, our adolescents and myself began to understand better compared to the previous visits.” (Parent, female, 47 years, third implementation month) To counteract these challenges, and following supervisory guidance, CHWs strengthened communication through repetition, contextualization, and participatory engagement to improve comprehension. Feedback on participant understanding was reviewed during supervision and used to refine communication approaches across CHWs. CHWs used familiar foods and everyday examples to reinforce understanding across visits, thereby modifying communication approaches while maintaining core nutrition messages and visual-aided counselling. “We started explaining using foods they see every day ‒ like vegetables, beans, and mangoes ‒ and repeated this in later visits until they understood.” (CHW, male, 56 years, fourth implementation month) Supervisory discussions also encouraged linking messages to adolescents’ lived experiences and increasing participation during sessions, supporting continued refinement of delivery practices over time. “With time we learned how to involve them more… which made the lessons easier to follow.” (CHW, female, 50 years, seventh implementation month) Outer setting: Resource-sensitive counselling adaptation Early implementation revealed constraints in applying dietary recommendations, but over time, counselling increasingly aligned with household resource realities through guided adaptation. Household economic conditions influenced the feasibility of adopting recommended dietary practices. Adolescents described challenges in accessing recommended foods due to financial constraints, highlighting limitations in implementing dietary advice. “They told us to eat eggs and fruits to stay healthy, but sometimes there is no money at home to buy them, so you just eat what is available.” (Adolescent, male, 15 years, second implementation month) Caregivers similarly emphasized reliance on available foods, reflecting household-level constraints that shaped dietary practices. “You may want to have fish or fruits for the children, but when you cannot afford them you just prepare what is there.” (Parent, female, 58 years, third implementation month) Adolescents further reported that household food choices were shaped by financial constraints, where even supportive caregivers could not always prioritize healthier options due to limited resources and competing household needs. “My mum supports us to eat well, but sometimes my father says there is no money for those foods.” (Adolescent, female, 17 years, seventh implementation month) Through supervisory discussions, participant feedback on limited access to recommended foods was reviewed, and CHWs were guided to align dietary advice with locally available resources while maintaining core nutrition messages. Supervisory discussions supported consistency in these counselling approaches across CHWs. CHWs emphasized affordable and locally available food options by modifying food examples and substitutions while preserving the intent of dietary recommendations. “We explain that even if they cannot buy expensive foods, they can use greens from the garden, beans, and groundnuts so the child still eats appropriately.” (CHW, female, 32 years, seventh implementation month) Inner setting and implementation process : Workload-responsive micro-planning Scheduling challenges were reported during early and mid-implementation, but CHWs progressively adopted micro-scheduling strategies to sustain delivery, with continued adjustment in later months. CHWs reported competing responsibilities that affected their ability to maintain planned visit schedules. CHWs described how overlapping responsibilities limited their ability to conduct household visits as planned. “Sometimes we have many activities in the community at the same time… you are expected to attend a meeting, support another health program, and still visit households.” (CHW, male, 61 years, first implementation month) They [CHW] also highlighted situations where they were required to be present in multiple locations simultaneously, which constrained delivery. “You can be called for immunization mobilisation or meetings… yet you also have homes to visit, so sometimes you find you are expected in two places at once.” (CHW, male, 45 years, third implementation month) Caregivers also described how visit timing needed to be adjusted to fit household routines, noting that initial visits occurred at inconvenient times but were later better aligned with their availability following prior discussion with CHWs. “During first visit, the CHW came when we were busy, but later she arranged and came at a better time when we were available. And for the subsequent visits, she started consulting me to know when both my adolescents and myself will be available before she could come.” (Parent, female, 44 years, third implementation month) As an adaptive response, CHWs were guided to reorganize delivery through micro-scheduling strategies to sustain coverage under constrained conditions. Supervisory discussions supported refinement of these scheduling approaches across CHWs. CHWs reorganized visits by clustering nearby households and adjusting timing to improve efficiency, thereby modifying visit scheduling and sequencing while maintaining intervention dose and continuity of delivery. “We started grouping two homes that are near each other and visiting them on the same day… that way we save time and make sure we don’t miss the lessons.” (CHW, female, 50 years, fifth implementation month) Outer and inner setting : Network-supported participant follow-up Participant absence and interrupted delivery became more evident during mid-implementation, prompting increased use of household and community networks to support continuity in later implementation. CHWs described engaging neighbours and local leaders to locate participants and support follow-up when adolescents were temporarily unavailable. “Sometimes you reach the home and find the adolescent has gone to stay with an aunt in another village. I would ask neighbours or the village local council to help locate them and follow up so they do not miss the lessons.” (CHW, male, 56 years, fourth implementation month) Through supervisory discussions, these follow-up approaches were refined to strengthen coordination with caregivers and community members across implementation periods. Caregivers also reported active engagement in supporting continuity of intervention messages within households between visits. “Even when the CHW is not around, we continue reminding the children about what they were taught and try to follow those practices at home.” (Parent, male, 53 years, sixth implementation month) Integrated adaptation–fidelity interplay during implementation To clarify how adaptive delivery processes were operationalized over time and how they interacted with fidelity, the linkage between contextual implementation challenges, observed fidelity patterns, supervisory reflection, and subsequent delivery adjustments is summarized (Table 4 ). Temporal patterns indicate when challenges and fidelity variations occurred and how responses were refined across implementation periods. Table 4 Interplay between contextual challenges, supervisory reflection, adaptive responses, and fidelity patterns during implementation Contextual challenges and initial fidelity patterns Supervisory reflection and guidance Adaptive responses applied over time Observed fidelity patterns following adaptive responses Missed visits and incomplete sessions, with lower dose delivered and participant responsiveness during early implementation (first–second months) Review of missed sessions and reduced participation; guidance on revisits, flexible scheduling, and follow-up Increasing use of revisits, evening scheduling, and coordination with caregivers and community members across implementation periods Higher session completion and participant responsiveness were observed during mid implementation (fourth–sixth months), with continued variation in later months (seventh–ninth months) Limited comprehension of abstract nutrition concepts, reflected in lower quality of delivery and participant engagement during early implementation (first–second months) Review of comprehension gaps; guidance on repetition, contextualization, and participatory communication Progressive use of familiar examples, repeated explanations, and participatory facilitation during mid and late implementation (fourth–seventh months) Greater clarity of delivery and participant responsiveness were observed during mid implementation (fourth–fifth months), sustained in later implementation (seventh–eighth months) Difficulty applying recommended dietary practices due to limited household resources, affecting feasibility of counselling during early to mid-implementation (second–fourth months) Review of feasibility concerns; guidance on aligning recommendations with locally available foods Increasing alignment of counselling with affordable and locally available foods during mid implementation (fourth–seventh months) Program differentiation remained high, with increased acceptability, and relevance of counselling across implementation periods (fourth–eighth months) Competing CHW responsibilities affecting adherence to planned schedules during mid implementation (fourth–fifth months) Review of scheduling constraints; guidance on clustering visits and adjusting timing Adoption of clustered visits and adjusted scheduling during mid implementation (fifth–seventh months) Continued delivery of sessions was observed despite competing demands, with variability in adherence and timing in later implementation (seventh–eighth months) Participant absence and interrupted delivery affecting continuity of engagement during mid implementation (fourth–fifth months) Review of follow-up challenges; guidance on engaging caregivers, neighbours, and local leaders Increased coordination with household and community networks for follow-up during mid implementation (fifth–seventh months) Participant engagement and continuity of exposure were observed from mid to later implementation (fourth–eighth months) Discussion This longitudinal mixed-methods implementation study examined how adaptive delivery and implementation fidelity were dynamically interrelated during the nine-month implementation of a CHW-led adolescent nutrition education intervention in rural Uganda. The study provides empirical evidence of a supervision-mediated adaptation–fidelity feedback process through which fidelity monitoring informed bounded delivery adaptations over time. By integrating prospective fidelity assessment with qualitative evidence on implementation processes, the findings suggest that adaptation and fidelity were not competing constructs but mutually informing processes shaped through structured supervisory reflection. Across implementation, observed delivery challenges and fidelity patterns informed guided delivery adjustments, which were reflected in subsequent delivery quality, participant responsiveness, and continuity of implementation. Fidelity trajectories reflected how CHWs navigated context-specific constraints during routine delivery and how these evolved over time. While early variability in dose delivered and participant responsiveness has been documented in community-based interventions [ 13 , 22 ], the observed progression in this study underscores that fidelity is shaped by how implementers respond to changing contextual conditions rather than by static adherence alone [ 36 ]. The evolution of adaptive strategies such as rescheduling and strengthened communication, alongside later variability under increased workload, suggests that implementation designs should explicitly anticipate temporal fluctuations. These patterns reinforce the importance of embedding flexibility within delivery protocols to sustain engagement under routine conditions. For practice and program design, this implies the need to build flexibility into delivery protocols, including planned revisits, adaptive scheduling, and mechanisms to sustain engagement under varying contextual demands. Beyond fidelity measurement, qualitative findings also provide insight into how feasibility, acceptability, and appropriateness are expressed through delivery processes. Flexible scheduling and micro-planning illustrate feasibility under routine CHW delivery conditions; participant responsiveness and caregiver engagement reflect acceptability; and resource-sensitive counselling reflects the perceived appropriateness of intervention messages within household food realities. Adjustments in communication, alignment of counselling with locally available resources, and reorganization of delivery processes further illustrate how implementation can remain responsive while preserving core intent [ 21 , 28 ]. These patterns reinforce that implementation strategies operate within broader socio-ecological conditions [ 37 ]. For implementation practice, this underscores the need to design interventions that clearly distinguish core functions from adaptable delivery forms, while equipping frontline workers with context-sensitive strategies such as flexible scheduling, follow-up mechanisms, and community-supported engagement. Supportive supervision emerged as a central mechanism through which adaptive delivery and fidelity were aligned over time. Rather than functioning solely as a monitoring tool, supervision provided a structured platform for reflection, feedback, and guided adjustment. Through this process, observed delivery challenges were reviewed and used to inform subsequent adjustments in delivery practices. This is consistent with evidence from community health systems where supervision supports learning and quality improvement [ 14 ] and facilitates alignment of delivery practices in CHW programs [ 13 ]. For policy and health systems strengthening, these findings point to the need to invest in supervision models that integrate real-time feedback, problem-solving, and decision support, rather than relying on compliance-oriented supervision alone. The present study provides a process-oriented perspective on how fidelity and adaptation can be managed during routine implementation. The observed pattern ‒ where implementation experiences inform reflection, leading to bounded adaptations that preserve core intervention functions ‒ supports a core functions/forms interpretation of fidelity and adaptation. Delivery forms were adjusted to fit contextual realities while core intervention components remained consistent across implementation. The longitudinal nature of this process further indicates that alignment between adaptation and fidelity evolves over time, rather than being achieved at a single point [ 36 ]. For research, this underscores the value of longitudinal and mixed-methods approaches that capture how implementation processes unfold, and highlights the need for analytic frameworks that explicitly examine interactions between context, supervision, adaptation, and fidelity in real-world settings. Study strengths and limitations This study has several strengths. The longitudinal mixed-methods design enabled examination of how adaptive implementation and fidelity evolve over time, addressing a key gap in implementation research that often relies on cross-sectional or single-time-point assessments. The integration of quantitative fidelity measures with qualitative data from CHWs, adolescents, and caregivers strengthened the credibility of findings and enabled in-depth understanding of how delivery processes, adaptive strategies, and observed fidelity patterns operated as interrelated processes. Fidelity assessment data were collected prospectively across implementation periods, rather than relying on retrospective accounts. Embedding the study within routine CHW delivery systems further enhances the relevance and applicability of the findings to real-world implementation contexts. However, fidelity assessments were based on periodic rather than continuous observations and may not have captured all session-level variation; this was mitigated through repeated observations across early, mid, and late implementation and triangulation with qualitative data. Fidelity observations were conducted by supervisors involved in implementation, which may have introduced observer or social desirability bias; standardized checklists and unannounced visits were used to minimize this risk. Although qualitative data were collected repeatedly, FGDs with adolescents and parents involved different participants across rounds; thus, observed changes reflect evolving implementation experiences across groups rather than individual-level change. This was addressed through purposive sampling and triangulation across CHWs, adolescents, and parents. Because adaptations were identified through qualitative accounts and supervision-linked interpretation, the study cannot attribute observed fidelity changes to specific adaptations, nor estimate independent effects of adaptive strategies on fidelity outcomes, instead providing an integrated longitudinal account of supervision, adaptation, and fidelity. Conclusion This study provides empirical evidence that adaptive delivery and implementation fidelity are best conceptualized as interdependent implementation processes rather than competing priorities. In this CHW-led adolescent nutrition intervention, fidelity monitoring, supportive supervision, and guided problem-solving supported a feedback process through which delivery adaptations were made while maintaining core intervention functions. These findings highlight the value of structured supervision systems in guiding bounded adaptation and sustaining fidelity in routine community health delivery. Declarations Trial registrations: The parent randomized controlled trial was prospectively registered with the Pan African Clinical Trials Registry (PACTR202501305580883) on 7 June 2024 . https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=30558 Ethical approval and consent to participate This study, part of the ARISE-NUTRINT (Africa Research, Implementation Science, and Education – Reducing nutrition-related NCDs in adolescence and youth) project, was conducted in accordance with the Declaration of Helsinki. Ethical approval was obtained from the Research and Ethics Committee at MakSPH (Ref: SPH-2023-460), and the study was registered with the Uganda National Council for Science and Technology (Ref: HS3481ES). Written informed consent was obtained from all adult participants (AYAs aged 18–24 years, parents or guardians, and CHWs). For adolescents aged 10–17 years, written informed consent was obtained from their parents or guardians, and assent from the adolescents. Participation was voluntary, and participants could withdraw at any time without consequence. Audio recordings and translated data were stored on password-protected, encrypted devices accessible only to the research team. Consent for publication Not applicable. Availability of data and materials The de-identified quantitative fidelity dataset supporting the findings of this study is provided as Supplementary Material 3 . Excerpts from qualitative transcripts sufficient to support the analytic claims are presented in the manuscript. Full de-identified qualitative transcripts are not publicly available due to ethical and confidentiality considerations but may be made available from the corresponding author on reasonable request, subject to applicable ethics and data protection requirements. Competing interests The authors declare no competing interests. Funding This study was conducted as part of the ARISE-NUTRINT project, a collaborative project between MakSPH in Uganda, and 13 other institutions in Africa, Europe and the Harvard School of Public Health in the United States of America. The project is funded by the European Union under Project Grant Number 101095616. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. Funding acquisition at MakSPH was led by DG and JB, Co-investigators on the ARISE-NUTRINT project. Authors’ contributions Conceptualization: TBu and RN; Data curation: TBu; Formal analysis: TBu; Funding acquisition: DG and JB; Investigation: TBu; Methodology: TBu, RN, EB, and SL; Validation: TBu; Visualization: TBu; Writing original draft: TBu; Review and Editing revised manuscript: TBu, EB, SL, JB, MMS, TBä, DG, and RN. Author details 1 Department of Epidemiology and Biostatistics, School of Public Health, Makerere University, Kampala, Uganda 2 Iowa State University-Uganda Program, Center for Sustainable Rural Livelihoods. P.O. Box 218 Kamuli, Uganda 3 Department of Community Health and Behavioural Sciences, School of Public Health, Makerere University, Kampala, Uganda 4 Department of Public Health and Nutrition, Faculty of Health Sciences, Victoria University, Kampala, Uganda. 5 Department of Psychiatry and Psychotherapy (Campus Charité Mitte), Charité – Universitätsmedizin, Berlin, Germany. 6 German Center for Mental Health (DZPG), Berlin, Germany. 7 Africa Academy for Public Health, Dar es Salaam, Tanzania. 8 Heidelberg Institute of Global Health (HIGH), Medical Faculty and University Hospital, Heidelberg University, Heidelberg, Germany. 9 Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Harvard University, Boston, USA. 10 Africa Health Research Institute (AHRI), Somkhele and Durban, South Africa. 11 Department of Disease Control and Environmental Health, School of Public Health, Makerere University, Kampala, Uganda. 12 Department of Preventive Medicine, College of Medicine, Korea University, Seoul, South Korea Acknowledgement The authors acknowledge the German Alliance for Global Health Research (GLOHRA), through PD Dr. Shannon McMahon, for awarding a short training scholarship to the first author to attend a one-week training in qualitative research in global health at the Heidelberg Institute of Global Health, Germany, in October 2024. This training contributed to strengthening the first author’s research skills applied in the present study. We also acknowledge the CHWs for leading the household-level implementation of the intervention, and the AYAs and their parents for their participation in this study. 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Examination of facilitators and barriers to home-based supplemental feeding with ready‐to‐use food for underweight children in western Uganda. Matern Child Nutr. 2012;8(1):115–29. Chambers DA, Glasgow RE, Stange KC. The dynamic sustainability framework: addressing the paradox of sustainment amid ongoing change. Implement Sci. 2013;8(1):117. Perez Jolles M, Lengnick-Hall R, Mittman BS. Core functions and forms of complex health interventions: a patient-centered medical home illustration. J Gen Intern Med. 2019;34(6):1032–8. von Thiele Schwarz U, Aarons GA, Hasson H. The Value Equation: Three complementary propositions for reconciling fidelity and adaptation in evidence-based practice implementation. BMC Health Serv Res. 2019;19(1):868. Carroll C, Patterson M, Wood S, Booth A, Rick J, Balain S. A conceptual framework for implementation fidelity. Implement Sci. 2007;2:1–9. Ikendi S. Impact of nutrition education centers on food and nutrition security in Kamuli District, Uganda. 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Campbell Syst Reviews. 2020;16(2):e1085. Moore GF, Audrey S, Barker M, Bond L, Bonell C, Hardeman W, Moore L, O’Cathain A, Tinati T, Wight D. Process evaluation of complex interventions: Medical Research Council guidance. bmj 2015, 350. Nilsen P. Making sense of implementation theories, models, and frameworks. Implementation Science 30. edn.: Springer; 2020. pp. 53–79. Kajungu D, Hirose A, Rutebemberwa E, Pariyo GW, Peterson S, Guwatudde D, Galiwango E, Tusubira V, Kaija J, Nareeba T, et al. Cohort Profile: The Iganga-Mayuge Health and Demographic Surveillance Site, Uganda (IMHDSS, Uganda). Int J Epidemiol. 2020;49(4):1082–g1082. Damschroder LJ, Aron DC, Keith RE, Kirsh SR, Alexander JA, Lowery JC. Fostering implementation of health services research findings into practice: a consolidated framework for advancing implementation science. Implement science: IS. 2009;4:50. Braun V, Clarke V. Using thematic analysis in psychology. Qualitative Res Psychol. 2006;3(2):77–101. Additional Declarations No competing interests reported. Supplementary Files SupplementaryMaterial1FidelityAssessmentChecklist.xlsx SupplementaryMaterial2FGDguidesCHWsAYAsandParents.docx SupplementaryMaterial3FidelityDataset.xlsx Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 15 May, 2026 Reviewers agreed at journal 14 May, 2026 Reviewers invited by journal 13 May, 2026 Editor assigned by journal 05 May, 2026 Submission checks completed at journal 04 May, 2026 First submitted to journal 03 May, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9602420","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":634031876,"identity":"3da80268-08b2-4998-9104-54efc8cf2df0","order_by":0,"name":"Thomas Buyinza","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA8UlEQVRIiWNgGAWjYDACCTB5gIGBGURXADEzcwNeHTyoWs6AtDASqwUEGNvAJH4t9tLNRzf8+HMnccNx3sMffs6rjeZvB2r5UbENty0yx9Ju9rY9S9xwmC/BsHfb8dwZhxkbGHvO3MbjsByzG7wNh4FaeAwSeLcdy20AamFmbMOv5eafPxAtB//OOZY7nxgtt3nYwFoMm3kbanI3ENRyIy3ttmzbM+OZh3mMmWWOHcjdCNRyEJ9f2GckH7v55s8d2b7zZ4w/vqmpy513/vDBBz8qcGuBA4UDYOowmDxAWD0QyDeAqTqiFI+CUTAKRsHIAgClTWSzhdrmNwAAAABJRU5ErkJggg==","orcid":"","institution":"Makerere University","correspondingAuthor":true,"prefix":"","firstName":"Thomas","middleName":"","lastName":"Buyinza","suffix":""},{"id":634031877,"identity":"0e8bb6ba-56dc-489a-ba59-6719d03563aa","order_by":1,"name":"Edward Buzigi","email":"","orcid":"","institution":"Makerere University","correspondingAuthor":false,"prefix":"","firstName":"Edward","middleName":"","lastName":"Buzigi","suffix":""},{"id":634031878,"identity":"b5c3ed18-6730-405e-be63-c25dd9f72093","order_by":2,"name":"Shuyan Liu","email":"","orcid":"","institution":"Berlin Institute of Health at Charité - Universitätsmedizin Berlin","correspondingAuthor":false,"prefix":"","firstName":"Shuyan","middleName":"","lastName":"Liu","suffix":""},{"id":634031882,"identity":"078e82ed-bd12-412c-b64d-41406905c136","order_by":3,"name":"Justine Bukenya","email":"","orcid":"","institution":"Makerere University","correspondingAuthor":false,"prefix":"","firstName":"Justine","middleName":"","lastName":"Bukenya","suffix":""},{"id":634031883,"identity":"1b18e645-707a-4626-baf7-8fef3286b4e1","order_by":4,"name":"Mary Mwanyika Sando","email":"","orcid":"","institution":"Africa Academy for Public Health","correspondingAuthor":false,"prefix":"","firstName":"Mary","middleName":"Mwanyika","lastName":"Sando","suffix":""},{"id":634031884,"identity":"cf0c09ea-8579-4821-84e7-c2729d06158c","order_by":5,"name":"Till Bärnighausen","email":"","orcid":"","institution":"Heidelberg University","correspondingAuthor":false,"prefix":"","firstName":"Till","middleName":"","lastName":"Bärnighausen","suffix":""},{"id":634031885,"identity":"fdb6d492-670a-4214-9a93-02fa1d5aca8b","order_by":6,"name":"David Guwatudde","email":"","orcid":"","institution":"Makerere University","correspondingAuthor":false,"prefix":"","firstName":"David","middleName":"","lastName":"Guwatudde","suffix":""},{"id":634031886,"identity":"848f11a5-8adc-4dc8-8f59-2bf897ec159d","order_by":7,"name":"Rawlance Ndejjo","email":"","orcid":"","institution":"Makerere University","correspondingAuthor":false,"prefix":"","firstName":"Rawlance","middleName":"","lastName":"Ndejjo","suffix":""}],"badges":[],"createdAt":"2026-05-03 20:23:29","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9602420/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9602420/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108464386,"identity":"08de07c3-86fa-4b3a-8ff1-131b66f2fb21","added_by":"auto","created_at":"2026-05-05 02:56:07","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":59236,"visible":true,"origin":"","legend":"\u003cp\u003eConceptual framework of supervision-mediated interaction between adaptive delivery and implementation fidelity in a CHW-led adolescent nutrition intervention. CFIR, Consolidated Framework for Implementation Research.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eKey:\u003c/strong\u003e--------- Feedback; ______ Direct pathway\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9602420/v1/cf5f6e033b537b526cf9a7b1.png"},{"id":108493640,"identity":"f0af6fe7-70c4-4752-8ce5-c024085092d3","added_by":"auto","created_at":"2026-05-05 10:01:08","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":76524,"visible":true,"origin":"","legend":"\u003cp\u003eMean fidelity component scores across early, mid, and late implementation\u003cem\u003e.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9602420/v1/7f9ddd0bf070f77187f957a2.png"},{"id":109203590,"identity":"533d1fb7-6e72-4e32-8d14-7709c58ec095","added_by":"auto","created_at":"2026-05-13 14:41:09","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":536205,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9602420/v1/9d3317ac-d7b5-4bb9-b051-e8751820fe2b.pdf"},{"id":108464385,"identity":"1ffbf629-c5be-4947-89e5-ff1e851c0a31","added_by":"auto","created_at":"2026-05-05 02:56:07","extension":"xlsx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":10140,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryMaterial1FidelityAssessmentChecklist.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-9602420/v1/215b3284864fae3d94a9b555.xlsx"},{"id":108464387,"identity":"089bac89-5196-411a-8640-274a77d4b7c3","added_by":"auto","created_at":"2026-05-05 02:56:08","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":20683,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryMaterial2FGDguidesCHWsAYAsandParents.docx","url":"https://assets-eu.researchsquare.com/files/rs-9602420/v1/3642d5599c69bda4ad950ffe.docx"},{"id":108494093,"identity":"90f90199-0374-4643-9b4e-540274e51ea0","added_by":"auto","created_at":"2026-05-05 10:02:34","extension":"xlsx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":13212,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryMaterial3FidelityDataset.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-9602420/v1/d170cdbb7cb86b95276971ec.xlsx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Balancing adaptive delivery and implementation fidelity over time: a longitudinal mixed-methods study of a community health worker–led adolescent nutrition intervention in Uganda","fulltext":[{"header":"Contributions to the Literature","content":"\u003cul\u003e\n \u003cli\u003eProvides longitudinal empirical evidence on how adaptive delivery and implementation fidelity are interrelated during routine delivery of a community health worker\u0026ndash;led intervention.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eConceptualizes a supervision-mediated adaptation\u0026ndash;fidelity feedback loop linking fidelity monitoring, reflective problem-solving, and bounded delivery adaptations.\u003c/li\u003e\n \u003cli\u003eDemonstrates an analytic approach for integrating prospective fidelity assessment with repeated qualitative data on adaptive delivery processes in low-resource community health systems.\u003c/li\u003e\n\u003c/ul\u003e"},{"header":"Background","content":"\u003cp\u003eAdolescents and young adults (AYAs) have increased nutritional requirements during a critical period of physical, cognitive, and psychosocial development [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. However, unhealthy and inadequate dietary patterns remain widespread globally, particularly in Sub-Saharan Africa (SSA), where structural constraints limit access to healthy foods [\u003cspan additionalcitationids=\"CR3 CR4 CR5\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. In Uganda, inadequate fruit and vegetable intake and low dietary diversity are common among AYAs [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. These patterns are shaped by low nutrition literacy and broader socio-ecological influences, underscoring the need for contextually appropriate, household-level interventions that engage adolescents alongside their caregivers [\u003cspan additionalcitationids=\"CR10 CR11\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCommunity health workers (CHWs) play a central role in preventive health delivery in low- and middle-income countries, including Uganda, where they provide health education, counselling, and linkage to services at the household level [\u003cspan additionalcitationids=\"CR14 CR15\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. In Uganda, CHWs ‒ commonly referred to as village health teams ‒ are lay community-based volunteers within the national health system [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] and are well positioned to reach adolescents, including those out of school. To address challenges in delivering adolescent-focused interventions through routine systems, a community-based adolescent nutrition education intervention was implemented through CHW platforms in Uganda as part of the ARISE-NUTRINT study [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. While embedding interventions within CHW systems enhances feasibility and sustainability [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e], it also exposes delivery to contextual constraints and changing community conditions that shape how interventions are implemented in practice [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eEffective implementation depends not only on intervention design but also on how interventions are delivered within complex, resource-constrained health systems [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. CHW-led programs often face contextual challenges, including competing livelihood demands, variability in implementer capacity and motivation, sociocultural norms, seasonal disruptions, and limited supervision [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. These factors shape how interventions are delivered in practice, often requiring implementers to adjust delivery processes to sustain implementation. While such adjustments may improve contextual fit, unguided changes ‒particularly those affecting core intervention components ‒ may compromise fidelity. At the same time, adaptations to delivery forms may be necessary to sustain implementation in real-world settings [\u003cspan additionalcitationids=\"CR27\" citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eImplementation fidelity, defined as the extent to which an intervention is delivered as intended, is critical for interpreting effectiveness [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. However, fidelity may vary as implementation conditions change and implementers respond to emerging challenges, creating tension between maintaining adherence to core components and allowing flexibility in delivery. This is particularly important because fidelity and adaptation are often treated as competing priorities, yet implementation theory suggests that adaptations can support fidelity when they preserve core functions while modifying delivery forms [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Despite increasing recognition of this interplay, much of the adolescent nutrition literature in SSA has focused on intervention effectiveness, with limited attention to how delivery is adjusted in practice, how such adjustments are guided, and how adaptation and fidelity interact during routine implementation [\u003cspan additionalcitationids=\"CR31 CR32 CR33 CR34\" citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eImplementation research has also often assessed determinants or fidelity at single time points, providing limited insight into how these processes evolve over time [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. Empirical evidence on how this balance is actively managed during implementation remains limited, especially in CHW-led interventions in low-resource settings. Understanding these dynamics is important for informing implementation design and scale-up of community-based interventions within routine health systems. This study examined how adaptive delivery and implementation fidelity interacted over time during the nine-month implementation of the CHW-led intervention in rural Uganda.\u003c/p\u003e"},{"header":"Methodology","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy setting\u003c/h2\u003e \u003cp\u003eThe study was conducted in rural Mayuge District within the Iganga\u0026ndash;Mayuge Health and Demographic Surveillance Site (HDSS) in Eastern Uganda [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. This setting is predominantly rural and characterized by subsistence farming, seasonal livelihood activities, and limited dietary diversity among adolescents [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Households in this context often experience fluctuations in food availability and access due to agricultural cycles and economic constraints, which shape dietary behaviours [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eStudy design\u003c/h3\u003e\n\u003cp\u003eThis was a longitudinal mixed-methods implementation study nested within a nine-month randomized controlled trial of a CHW\u0026ndash;led adolescent nutrition education intervention, delivered from 15 May 2025 to 16 January 2026. The study combined prospective quantitative fidelity observations with repeated qualitative data collection to examine adaptive delivery processes and contextual influences across early (months 1\u0026ndash;3), mid (months 4\u0026ndash;6), and late (months 7\u0026ndash;9) implementation. This design enabled examination of how adaptive delivery processes and implementation fidelity evolved over time under routine conditions.\u003c/p\u003e\n\u003ch3\u003eOverview of the intervention and implementation strategies\u003c/h3\u003e\n\u003cp\u003eDetails of the intervention and implementation strategies are reported elsewhere [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Briefly, this was a community-based adolescent nutrition education intervention delivered by CHWs to adolescents and their caregivers at the household level. The intervention comprised nine sequential monthly modules covering balanced diet, essential vitamins and minerals, reduction of sugar-sweetened beverages, correction of food-related myths, and prevention of anaemia. Each module was delivered during a structured household session using a visual-aided flyer. Sessions followed a standardized flow guided by standard operating procedures (SOPs), incorporating explanation of key messages, participatory discussion, and caregiver engagement to support household-level application. Sessions lasted approximately 40\u0026ndash;50 minutes, and flyers were left with households for ongoing reference.\u003c/p\u003e \u003cp\u003eFor this study, core intervention functions were predefined as delivery of the nine modules, engagement of the adolescent, use of visual-aided counselling, caregiver involvement, and reinforcement of key nutrition messages. Adaptable delivery forms included visit timing, sequencing of revisits, communication approaches, locally feasible food substitutions, and follow-up arrangements. Core components were maintained to support fidelity, while allowing flexibility in delivery frequency and scheduling to accommodate contextual constraints.\u003c/p\u003e \u003cp\u003e The main implementation strategies examined included SOP-guided delivery, supportive supervision, fidelity monitoring, feedback/debrief meetings, and guided problem-solving. Throughout implementation, CHWs received supportive supervision through observation of selected sessions using fidelity checklists and monthly debrief meetings. Supervisors reviewed delivery progress, discussed challenges, and guided context-appropriate adjustments while maintaining core components. Supportive supervision was treated as the central strategy through which fidelity observations and delivery challenges informed bounded adaptations.\u003c/p\u003e\n\u003ch3\u003eStudy population and sampling\u003c/h3\u003e\n\u003cp\u003eThe study population comprised three categories of respondents, including individuals who delivered or experienced the intervention: the implementers of the intervention (CHWs), intervention recipients (AYAs), and household influencers (parents of participating AYAs).\u003c/p\u003e \u003cp\u003ePurposive sampling was used, guided by participants\u0026rsquo; roles in implementation, level of exposure to the intervention, and ability to provide in-depth insights into implementation processes. All ten CHWs who implemented the intervention were included, and all consented to participate. For this intervention, CHWs received structured training on the use of visual-aided materials, facilitation of participatory discussions, and adherence to standard operating procedures. Their dual role as community members and implementers positioned them to take on supervised adaptive delivery strategies, in response to contextual challenges.\u003c/p\u003e \u003cp\u003eAYA and parent/guardian participants were recruited at selected time points across early, mid, and late implementation to capture variation in age, sex, schooling status, and caregiving context. AYAs were grouped into three age categories (10\u0026ndash;14, 15\u0026ndash;19, and 20\u0026ndash;24 years) to reflect developmental differences and ensure equal inclusion of both in-school and out-of-school participants.\u003c/p\u003e \u003cp\u003e Across the study, 14 focus group discussions (FGDs) were conducted: six with CHWs, six with AYAs, and two with parents or guardians. The FGDs for CHWs followed a panel design involving the same ten participants across repeated rounds, to enable assessment of implementation learning over time. The FGDs for AYAs and parents involved different participants at selected time points to capture diverse recipient experiences across implementation periods while reducing repeated-participation burden. Each FGD included 8\u0026ndash;10 participants, and 60 unique participants contributed to the qualitative component. Sampling and data collection proceeded iteratively until sufficient depth and variation in perspectives were achieved across participant groups.\u003c/p\u003e\n\u003ch3\u003eConceptual framework\u003c/h3\u003e\n\u003cp\u003eWe synthesized and framed an adaptation\u0026ndash;fidelity feedback framework, drawing on the Consolidated Framework for Implementation Research (CFIR) [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e], and Carroll\u0026rsquo;s fidelity framework [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], to guide this study. The framework assumes that fidelity monitoring identifies delivery challenges, supervision creates a space for reflection and problem-solving, and agreed delivery adaptations are then applied and reflected in subsequent fidelity patterns. Contextual influences, organized using the CFIR, are conceptualized as the conditions within which implementation occurs, including factors related to the outer setting, inner setting, intervention characteristics, characteristics of individuals, and implementation processes (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). In this framework, implementation is conceptualized as a dynamic process in which contextual influences shape fidelity challenges, supervision mediates reflection and problem-solving, and bounded adaptations influence subsequent fidelity patterns, creating an iterative feedback loop over time.\u003c/p\u003e \u003cp\u003eWithin this framework, intervention delivery is understood as responsive to contextual conditions, with adjustments in delivery processes occurring during implementation. Implementation fidelity assessment draws on Carroll et al.\u0026rsquo;s framework, which defines fidelity across adherence, dose delivered, quality of delivery, participant responsiveness, and program differentiation. Adaptive implementation and fidelity are viewed as dynamically interrelated processes, with adaptations focused on delivery forms while preserving core intervention functions.\u003c/p\u003e \u003cp\u003eImplementation experiences, including observed delivery challenges and fidelity patterns, inform reflection and problem-solving through supportive implementation processes, which in turn shape subsequent delivery adjustments. These adjustments are expected to influence later fidelity dimensions, creating an ongoing feedback process through which bounded adaptation evolved alongside implementation fidelity patterns over time under routine conditions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eData collection procedures\u003c/h2\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003eImplementation fidelity\u003c/h2\u003e \u003cp\u003eImplementation fidelity data were collected prospectively during routine intervention delivery from June 2025 to January 2026, covering the full nine-month implementation period. Fidelity monitoring was conducted during supervisory field visits. Each of the ten CHWs was directly observed once in each of the three implementation periods (months 1\u0026ndash;3, 4\u0026ndash;6, and 7\u0026ndash;9) during real-time intervention delivery sessions, resulting in three observations per CHW. This enabled assessment of variation in fidelity across implementation periods under routine delivery conditions.\u003c/p\u003e \u003cp\u003eFidelity was assessed using a structured observation checklist (\u003cb\u003eSupplementary Material 1\u003c/b\u003e) aligned with the five components of Carroll et al.\u0026rsquo;s framework: adherence, dose delivered, quality of delivery, participant responsiveness, and program differentiation [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Each component was measured using multiple items rated on a 5-point Likert scale (1\u0026thinsp;=\u0026thinsp;strongly disagree, 2\u0026thinsp;=\u0026thinsp;disagree, 3\u0026thinsp;=\u0026thinsp;neutral, 4\u0026thinsp;=\u0026thinsp;agree, and 5\u0026thinsp;=\u0026thinsp;strongly agree), based on predefined scoring criteria. Scores were summarized descriptively to compare relative fidelity levels across implementation periods, rather than to test for statistical significance.\u003c/p\u003e \u003cp\u003eFidelity assessments were conducted by a trained field implementation supervisor during routine, unannounced visits and were recorded contemporaneously. Supervision included observation of delivery and structured reflection and feedback discussions based on observed implementation challenges. Post-observation discussions focused on identifying operational challenges and providing guidance on delivery practices.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e\n\u003ch3\u003eAdaptive delivery processes\u003c/h3\u003e\n\u003cp\u003eQualitative data were collected to assess adaptive delivery processes and how delivery adjustments related to core intervention components during ongoing intervention delivery. Six FGDs were conducted with the ten CHWs after the first, second, third, fourth, fifth, and seventh implementation months. To capture perspectives of intervention recipients and households, six FGDs were conducted with AYAs and two with parents or guardians, with different participants engaged across rounds. Parent FGDs were conducted in the third and sixth months. Among AYAs, FGDs with those aged 10\u0026ndash;14 and 15\u0026ndash;19 years were conducted in the second month, those aged 20\u0026ndash;24 and 10\u0026ndash;14 years in the fourth month, and those aged 15\u0026ndash;19 and 20\u0026ndash;24 years in the seventh month. Different AYA age groups were purposively engaged at different time points to capture variation across developmental stages and implementation periods while minimizing repeat participation.\u003c/p\u003e \u003cp\u003e All FGDs were guided by semi-structured discussion guides informed by the CFIR (Supplementary Material 2) and conducted in Lusoga by a trained three-member research team experienced in qualitative data collection. Each session was audio-recorded with informed consent and lasted between 60 and 90 minutes. Discussions were held in private community venues at times convenient to participants. Moderators were independent of program implementation. Although CHWs and local leaders supported participant recruitment and scheduling, they did not attend discussions. All audio recordings were transcribed verbatim in \u003cem\u003eLusoga\u003c/em\u003e and translated into English. Translations were cross-checked by team members fluent in both languages, and transcripts were pseudonymized and de-identified prior to analysis.\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eData management and analysis\u003c/h2\u003e \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003eImplementation fidelity\u003c/h2\u003e \u003cp\u003eQuantitative fidelity data were entered, cleaned, and analyzed using Stata version 17.0. Composite fidelity scores were calculated by summing the five component scores (range 5\u0026ndash;25). Scores were categorized as high (21\u0026ndash;25), moderate (16\u0026ndash;20), or low (\u0026le;\u0026thinsp;15). Descriptive statistics (means, frequencies, and percentages) were used to summarize fidelity across implementation periods. Component-level analyses were conducted to describe performance across fidelity domains.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eAdaptive delivery processes\u003c/h2\u003e \u003cp\u003eAll audio-recorded discussions were transcribed verbatim in \u003cem\u003eLusoga\u003c/em\u003e and translated into English by trained members of the research team and cross-checked by another team member. To ensure translation accuracy, an additional researcher independently reviewed selected transcripts against the original audio recordings. Transcripts were anonymized through removal of personal identifiers and assignment of pseudonyms.\u003c/p\u003e \u003cp\u003eThe transcripts were analyzed using NVivo version 12. Analysis followed a hybrid deductive\u0026ndash;inductive thematic approach, informed by Braun and Clarke\u0026rsquo;s phases of thematic analysis [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. The analysis focused on adaptive delivery processes, delivery forms modified, and whether core intervention components were maintained, with the CFIR used to organize these processes.\u003c/p\u003e \u003cp\u003eThree researchers independently read all transcripts multiple times to achieve data immersion and developed initial analytic memos. This informed development of an initial codebook, which was iteratively refined through team discussions. Open coding was first applied to identify patterns in delivery processes. Subsequently, CFIR domains were used to organize adaptive delivery processes across intervention characteristics, outer setting, inner setting, characteristics of individuals, and implementation process domains.\u003c/p\u003e \u003cp\u003eEach transcript was coded independently by at least two research team members. Coding discrepancies were resolved through consensus discussions involving all three analysts, with reference to analytic memos and original transcripts where necessary. Codes were grouped into subthemes and examined across implementation periods to describe variation over time. An audit trail comprising codebooks, analytic memos, and consensus records was maintained. All de-identified data were stored on password-protected servers.\u003c/p\u003e \u003cp\u003eTo integrate quantitative and qualitative findings, fidelity results from early, mid, and late implementation were interpreted alongside qualitative accounts of adaptive delivery processes collected during corresponding implementation periods. Integration focused on how fidelity patterns, delivery challenges, supervisory reflection, and adaptive responses interacted over time.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eSocio-demographic characteristics of participants\u003c/h2\u003e \u003cp\u003eResults are presented in four parts: participant characteristics, fidelity patterns over time, adaptive delivery processes, and integrated evidence on how supervision-guided adaptations aligned with fidelity patterns across implementation.\u003c/p\u003e \u003cp\u003eA total of 60 participants were included: 30 AYAs, 20 parents or guardians, and 10 CHWs (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Most AYAs (28/30) had attained primary or secondary education. All CHWs were aged 25 years and above and had at least primary education. Parents were predominantly married or cohabiting. Across participant groups, most individuals resided in households of 5\u0026ndash;10 members (n\u0026thinsp;=\u0026thinsp;38).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSocio-demographic characteristics of participants (n\u0026thinsp;=\u0026thinsp;60)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCharacteristic\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAYAs\u003c/p\u003e \u003cp\u003en\u0026thinsp;=\u0026thinsp;30\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eParents/Guardians\u003c/p\u003e \u003cp\u003en\u0026thinsp;=\u0026thinsp;20\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCHWs\u003c/p\u003e \u003cp\u003en\u0026thinsp;=\u0026thinsp;10\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOverall\u003c/p\u003e \u003cp\u003en\u0026thinsp;=\u0026thinsp;60\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge Group\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u0026ndash;14 years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15\u0026ndash;19 years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e20\u0026ndash;24 years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e25 years and above\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSchooling status (AYAs only)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIn-school\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOut of school\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHighest education attained\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePrimary and below\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSecondary\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTertiary\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHousehold size\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;5 people\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u0026ndash;10 people\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;10 people\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMarital status\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSingle/never married\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMarried or cohabiting\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSeparated/Divorced\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDisability\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e58\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eEmployment\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFormal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInformal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e33\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNot working\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eImplementation fidelity across the nine-month implementation period\u003c/h2\u003e \u003cp\u003eImplementation fidelity varied over the nine-month implementation period (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). During months 1\u0026ndash;3, two of the 10 CHWs were categorized as having high implementation fidelity, six as moderate, and two as low. During months 4\u0026ndash;6, six CHWs were categorized as implementing with high fidelity, and none were classified as having low fidelity. By months 7\u0026ndash;9, four CHWs were categorized as implementing with high fidelity, and three were classified as having low fidelity. Overall, fidelity was highest during the mid-implementation period, with low, moderate, and high-fidelity levels observed in the late period.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eOverall implementation fidelity levels over time\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFidelity level\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMonths 1\u0026ndash;3 (early) n (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMonths 4\u0026ndash;6 (mid) n (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMonths 7\u0026ndash;9 (late) n (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOverall n (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHigh fidelity (21\u0026ndash;25)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (20.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6 (60.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4 (40.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e12 (40.0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eModerate fidelity (16\u0026ndash;20)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6 (60.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4 (40.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3 (30.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13 (43.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLow fidelity (\u0026le;\u0026thinsp;15)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (20.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3 (30.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5 (16.7)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTotal assessments\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e10 (100)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e10 (100)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e10 (100)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e30 (100)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eComponents of fidelity across the implementation period\u003c/h2\u003e \u003cp\u003eComponent-level analysis showed variation in fidelity domains over time (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). During early implementation, adherence averaged 3.6 (SD 0.7), increasing to 4.3 (SD 0.5) during the mid-implementation phase, and then decreasing slightly to 3.9 (SD 0.6) during the late phase. Similar patterns were observed for dose delivered (3.4, 4.2, 3.7) and participant responsiveness (3.2, 4.0, 3.4). Quality of delivery increased from 3.7 (SD 0.6) in early implementation to 4.4 (SD 0.5) in the mid-implementation phase and remained relatively high during the late phase (4.1, SD 0.6). Program differentiation remained consistently high across the implementation period (4.2, 4.5, 4.4). Overall, fidelity component scores were highest during the mid-implementation phase.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eAdaptive delivery processes and preservation of core intervention components\u003c/h2\u003e \u003cp\u003eFive themes were identified, reflecting adaptive delivery processes across the nine-month implementation period: flexible scheduling and revisits; contextualized reinforcement of complex content; resource-sensitive counselling adaptation; workload-responsive micro-planning; and network-supported participant follow-up (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e Adaptive delivery involved modifications to delivery forms while maintaining core intervention components and was shaped through structured supervisory discussions that reviewed delivery experiences, identified emerging challenges, and guided context-appropriate adjustments. Observed delivery challenges and fidelity patterns informed supervisory reflection, which in turn shaped subsequent delivery practices. Across implementation, adaptations were bounded to preserve core intervention functions while allowing flexibility in delivery. These adaptive processes evolved alongside changes in fidelity dimensions, including adherence, quality of delivery, and participant responsiveness, indicating a dynamic feedback process over time.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAdaptive delivery processes, delivery forms modified, and core components protected\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThemes (adaptive delivery process)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDescription of the adaptation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDelivery form modified\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCore component protected\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOuter setting\u003c/b\u003e: Flexible scheduling and revisits\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAdjusting home visit timing, conducting revisits, and coordinating with participants to address availability constraints due to schooling, livelihood activities, and mobility\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eVisit timing, revisits, participant follow-up arrangements\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCompletion of monthly module exposure and target adolescent engagement\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIntervention and individual characteristics\u003c/b\u003e: Contextualized reinforcement of complex content\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eReinforcing key messages through repetition and use of locally relevant examples to improve comprehension of complex intervention concepts\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCommunication approach, examples used, repetition of explanations\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eKey nutrition messages, visual-aided counselling, and participant comprehension\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOuter setting\u003c/b\u003e: Resource-sensitive counselling adaptation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAligning dietary recommendations with locally available and affordable foods while maintaining core intervention intent\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLocally feasible food examples and substitutions\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCore dietary messages on diversity, healthier choices, and anaemia prevention\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInner setting and implementation process\u003c/b\u003e: Workload-responsive micro-planning\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eClustering household visits and adjusting schedules to manage competing CHW responsibilities and sustain delivery continuity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCHW visit scheduling, clustering of nearby households, delivery sequencing\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIntervention dose, continuity of delivery, and SOP-guided session structure\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOuter and inner setting\u003c/b\u003e: Network-supported participant follow-up\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eEngaging caregivers, neighbours, and local leaders to support participant follow-up and continuity of intervention exposure\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFollow-up pathways, caregiver/community contact mechanisms\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eParticipant retention, caregiver involvement, and continuity of exposure\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003eOuter setting: Flexible scheduling and revisit mechanisms\u003c/h2\u003e \u003cp\u003eIn early implementation, participant availability constrained delivery, but by mid-implementation, CHWs increasingly applied structured rescheduling strategies, with further refinement observed in later months. Participant availability was shaped by livelihood activities, school attendance, and temporary mobility, which constrained the ability of CHWs to conduct household sessions as planned.\u003c/p\u003e \u003cp\u003eDuring the first implementation month (May 2025), rainfall and agricultural labour demands disrupted planned visits and reduced daytime household availability, limiting opportunities for delivery.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;Sometimes it rains when we are already on the way to deliver the education message to the households, so we fail to implement that day.\u0026rdquo;\u003c/em\u003e (CHW, male, 32 years, first implementation month)\u003c/p\u003e \u003cp\u003eParents also described how livelihood activities limited their availability during the day, requiring CHWs to adjust visit timing.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;Sometimes during the day, we are not at home because we go to the farm or to work, so when they [CHWs] come and miss us, they have to return later.\u0026rdquo;\u003c/em\u003e (Parent, female, 41 years, third implementation month)\u003c/p\u003e \u003cp\u003eRelatedly, adolescents also noted that their availability, particularly due to schooling, influenced scheduling of visits.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;Sometimes I am at school or away, so they tell my parent they will come back when I am around.\u0026rdquo;\u003c/em\u003e (Adolescent, female, 14 years, fourth implementation month)\u003c/p\u003e \u003cp\u003eIn response to these challenges, CHWs adjusted by returning later in the day or rescheduling visits to subsequent days to ensure sessions were completed. Missed visits and incomplete sessions were reviewed during supervision, which guided refinement of scheduling approaches across CHWs. CHWs also addressed temporary relocation by coordinating with caregivers and community members to support follow-up, thereby maintaining continuity of module delivery while modifying visit timing and revisit patterns.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;If we reach and find they have gone to the garden, we return in the evening or come back the next day so that we find them at home.\u0026rdquo;\u003c/em\u003e (CHW, female, 49 years, fourth implementation month)\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003eIntervention and individual characteristics: Contextualized reinforcement of complex content\u003c/h2\u003e \u003cp\u003eInitial challenges in explaining certain concepts during early implementation gave way to more effective, contextualized communication approaches during mid and late implementation. Some intervention topics were initially difficult for adolescents and their parents to understand, particularly those perceived as abstract or not directly observable in daily life.\u003c/p\u003e \u003cp\u003eCHWs described initial difficulties in explaining certain topics, particularly where adolescents could not easily relate them to everyday experiences.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;Training on anaemia was hard at first because the adolescents did not know that poor diet quality and worms can make them have little blood in their bodies.\u0026rdquo;\u003c/em\u003e (CHW, male, 56 years, first implementation month)\u003c/p\u003e \u003cp\u003eBoth CHWs and the intervention recipients (adolescents and parents) described initial difficulties in understanding some nutrition concepts before repeated explanation.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;At first I did not understand some of the lessons even though they were in Lusoga language, but when they kept explaining and using examples we see at home, I started to understand.\u0026rdquo;\u003c/em\u003e (Young adult, female, 20 years, third implementation month)\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;When they explain slowly and repeat, our adolescents and myself began to understand better compared to the previous visits.\u0026rdquo;\u003c/em\u003e (Parent, female, 47 years, third implementation month)\u003c/p\u003e \u003cp\u003e To counteract these challenges, and following supervisory guidance, CHWs strengthened communication through repetition, contextualization, and participatory engagement to improve comprehension. Feedback on participant understanding was reviewed during supervision and used to refine communication approaches across CHWs. CHWs used familiar foods and everyday examples to reinforce understanding across visits, thereby modifying communication approaches while maintaining core nutrition messages and visual-aided counselling.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;We started explaining using foods they see every day ‒ like vegetables, beans, and mangoes ‒ and repeated this in later visits until they understood.\u0026rdquo;\u003c/em\u003e (CHW, male, 56 years, fourth implementation month)\u003c/p\u003e \u003cp\u003eSupervisory discussions also encouraged linking messages to adolescents\u0026rsquo; lived experiences and increasing participation during sessions, supporting continued refinement of delivery practices over time.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;With time we learned how to involve them more\u0026hellip; which made the lessons easier to follow.\u0026rdquo;\u003c/em\u003e (CHW, female, 50 years, seventh implementation month)\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003eOuter setting: Resource-sensitive counselling adaptation\u003c/h2\u003e \u003cp\u003eEarly implementation revealed constraints in applying dietary recommendations, but over time, counselling increasingly aligned with household resource realities through guided adaptation. Household economic conditions influenced the feasibility of adopting recommended dietary practices.\u003c/p\u003e \u003cp\u003eAdolescents described challenges in accessing recommended foods due to financial constraints, highlighting limitations in implementing dietary advice.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;They told us to eat eggs and fruits to stay healthy, but sometimes there is no money at home to buy them, so you just eat what is available.\u0026rdquo;\u003c/em\u003e (Adolescent, male, 15 years, second implementation month)\u003c/p\u003e \u003cp\u003eCaregivers similarly emphasized reliance on available foods, reflecting household-level constraints that shaped dietary practices.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;You may want to have fish or fruits for the children, but when you cannot afford them you just prepare what is there.\u0026rdquo;\u003c/em\u003e (Parent, female, 58 years, third implementation month)\u003c/p\u003e \u003cp\u003eAdolescents further reported that household food choices were shaped by financial constraints, where even supportive caregivers could not always prioritize healthier options due to limited resources and competing household needs.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;My mum supports us to eat well, but sometimes my father says there is no money for those foods.\u0026rdquo;\u003c/em\u003e (Adolescent, female, 17 years, seventh implementation month)\u003c/p\u003e \u003cp\u003e Through supervisory discussions, participant feedback on limited access to recommended foods was reviewed, and CHWs were guided to align dietary advice with locally available resources while maintaining core nutrition messages. Supervisory discussions supported consistency in these counselling approaches across CHWs. CHWs emphasized affordable and locally available food options by modifying food examples and substitutions while preserving the intent of dietary recommendations.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;We explain that even if they cannot buy expensive foods, they can use greens from the garden, beans, and groundnuts so the child still eats appropriately.\u0026rdquo;\u003c/em\u003e (CHW, female, 32 years, seventh implementation month)\u003c/p\u003e \u003cp\u003e \u003cb\u003eInner setting and implementation process\u003c/b\u003e: \u003cb\u003eWorkload-responsive micro-planning\u003c/b\u003e\u003c/p\u003e \u003cp\u003eScheduling challenges were reported during early and mid-implementation, but CHWs progressively adopted micro-scheduling strategies to sustain delivery, with continued adjustment in later months. CHWs reported competing responsibilities that affected their ability to maintain planned visit schedules.\u003c/p\u003e \u003cp\u003eCHWs described how overlapping responsibilities limited their ability to conduct household visits as planned.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;Sometimes we have many activities in the community at the same time\u0026hellip; you are expected to attend a meeting, support another health program, and still visit households.\u0026rdquo;\u003c/em\u003e (CHW, male, 61 years, first implementation month)\u003c/p\u003e \u003cp\u003eThey [CHW] also highlighted situations where they were required to be present in multiple locations simultaneously, which constrained delivery.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;You can be called for immunization mobilisation or meetings\u0026hellip; yet you also have homes to visit, so sometimes you find you are expected in two places at once.\u0026rdquo;\u003c/em\u003e (CHW, male, 45 years, third implementation month)\u003c/p\u003e \u003cp\u003eCaregivers also described how visit timing needed to be adjusted to fit household routines, noting that initial visits occurred at inconvenient times but were later better aligned with their availability following prior discussion with CHWs.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;During first visit, the CHW came when we were busy, but later she arranged and came at a better time when we were available. And for the subsequent visits, she started consulting me to know when both my adolescents and myself will be available before she could come.\u0026rdquo;\u003c/em\u003e (Parent, female, 44 years, third implementation month)\u003c/p\u003e \u003cp\u003eAs an adaptive response, CHWs were guided to reorganize delivery through micro-scheduling strategies to sustain coverage under constrained conditions. Supervisory discussions supported refinement of these scheduling approaches across CHWs. CHWs reorganized visits by clustering nearby households and adjusting timing to improve efficiency, thereby modifying visit scheduling and sequencing while maintaining intervention dose and continuity of delivery.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;We started grouping two homes that are near each other and visiting them on the same day\u0026hellip; that way we save time and make sure we don\u0026rsquo;t miss the lessons.\u0026rdquo;\u003c/em\u003e (CHW, female, 50 years, fifth implementation month)\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003e\u003cb\u003eOuter and inner setting\u003c/b\u003e: \u003cb\u003eNetwork-supported participant follow-up\u003c/b\u003e\u003c/h2\u003e \u003cp\u003eParticipant absence and interrupted delivery became more evident during mid-implementation, prompting increased use of household and community networks to support continuity in later implementation.\u003c/p\u003e \u003cp\u003eCHWs described engaging neighbours and local leaders to locate participants and support follow-up when adolescents were temporarily unavailable.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;Sometimes you reach the home and find the adolescent has gone to stay with an aunt in another village. I would ask neighbours or the village local council to help locate them and follow up so they do not miss the lessons.\u0026rdquo;\u003c/em\u003e (CHW, male, 56 years, fourth implementation month)\u003c/p\u003e \u003cp\u003eThrough supervisory discussions, these follow-up approaches were refined to strengthen coordination with caregivers and community members across implementation periods. Caregivers also reported active engagement in supporting continuity of intervention messages within households between visits.\u003c/p\u003e \u003cp\u003e \u003cem\u003e\u0026ldquo;Even when the CHW is not around, we continue reminding the children about what they were taught and try to follow those practices at home.\u0026rdquo;\u003c/em\u003e (Parent, male, 53 years, sixth implementation month)\u003c/p\u003e \u003cdiv id=\"Sec23\" class=\"Section3\"\u003e \u003ch2\u003eIntegrated adaptation\u0026ndash;fidelity interplay during implementation\u003c/h2\u003e \u003cp\u003eTo clarify how adaptive delivery processes were operationalized over time and how they interacted with fidelity, the linkage between contextual implementation challenges, observed fidelity patterns, supervisory reflection, and subsequent delivery adjustments is summarized (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Temporal patterns indicate when challenges and fidelity variations occurred and how responses were refined across implementation periods.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003e\u003cb\u003eInterplay between contextual challenges, supervisory reflection, adaptive responses, and fidelity patterns during implementation\u003c/b\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eContextual challenges and initial fidelity patterns\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSupervisory reflection and guidance\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAdaptive responses applied over time\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eObserved fidelity patterns following adaptive responses\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMissed visits and incomplete sessions, with lower dose delivered and participant responsiveness during early implementation (first\u0026ndash;second months)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eReview of missed sessions and reduced participation; guidance on revisits, flexible scheduling, and follow-up\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eIncreasing use of revisits, evening scheduling, and coordination with caregivers and community members across implementation periods\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHigher session completion and participant responsiveness were observed during mid implementation (fourth\u0026ndash;sixth months), with continued variation in later months (seventh\u0026ndash;ninth months)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLimited comprehension of abstract nutrition concepts, reflected in lower quality of delivery and participant engagement during early implementation (first\u0026ndash;second months)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eReview of comprehension gaps; guidance on repetition, contextualization, and participatory communication\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eProgressive use of familiar examples, repeated explanations, and participatory facilitation during mid and late implementation (fourth\u0026ndash;seventh months)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eGreater clarity of delivery and participant responsiveness were observed during mid implementation (fourth\u0026ndash;fifth months), sustained in later implementation (seventh\u0026ndash;eighth months)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDifficulty applying recommended dietary practices due to limited household resources, affecting feasibility of counselling during early to mid-implementation (second\u0026ndash;fourth months)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eReview of feasibility concerns; guidance on aligning recommendations with locally available foods\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eIncreasing alignment of counselling with affordable and locally available foods during mid implementation (fourth\u0026ndash;seventh months)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eProgram differentiation remained high, with increased acceptability, and relevance of counselling across implementation periods (fourth\u0026ndash;eighth months)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCompeting CHW responsibilities affecting adherence to planned schedules during mid implementation (fourth\u0026ndash;fifth months)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eReview of scheduling constraints; guidance on clustering visits and adjusting timing\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAdoption of clustered visits and adjusted scheduling during mid implementation (fifth\u0026ndash;seventh months)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eContinued delivery of sessions was observed despite competing demands, with variability in adherence and timing in later implementation (seventh\u0026ndash;eighth months)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParticipant absence and interrupted delivery affecting continuity of engagement during mid implementation (fourth\u0026ndash;fifth months)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eReview of follow-up challenges; guidance on engaging caregivers, neighbours, and local leaders\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eIncreased coordination with household and community networks for follow-up during mid implementation (fifth\u0026ndash;seventh months)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eParticipant engagement and continuity of exposure were observed from mid to later implementation (fourth\u0026ndash;eighth months)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis longitudinal mixed-methods implementation study examined how adaptive delivery and implementation fidelity were dynamically interrelated during the nine-month implementation of a CHW-led adolescent nutrition education intervention in rural Uganda. The study provides empirical evidence of a supervision-mediated adaptation\u0026ndash;fidelity feedback process through which fidelity monitoring informed bounded delivery adaptations over time. By integrating prospective fidelity assessment with qualitative evidence on implementation processes, the findings suggest that adaptation and fidelity were not competing constructs but mutually informing processes shaped through structured supervisory reflection. Across implementation, observed delivery challenges and fidelity patterns informed guided delivery adjustments, which were reflected in subsequent delivery quality, participant responsiveness, and continuity of implementation.\u003c/p\u003e \u003cp\u003eFidelity trajectories reflected how CHWs navigated context-specific constraints during routine delivery and how these evolved over time. While early variability in dose delivered and participant responsiveness has been documented in community-based interventions [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], the observed progression in this study underscores that fidelity is shaped by how implementers respond to changing contextual conditions rather than by static adherence alone [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. The evolution of adaptive strategies such as rescheduling and strengthened communication, alongside later variability under increased workload, suggests that implementation designs should explicitly anticipate temporal fluctuations. These patterns reinforce the importance of embedding flexibility within delivery protocols to sustain engagement under routine conditions. For practice and program design, this implies the need to build flexibility into delivery protocols, including planned revisits, adaptive scheduling, and mechanisms to sustain engagement under varying contextual demands.\u003c/p\u003e \u003cp\u003eBeyond fidelity measurement, qualitative findings also provide insight into how feasibility, acceptability, and appropriateness are expressed through delivery processes. Flexible scheduling and micro-planning illustrate feasibility under routine CHW delivery conditions; participant responsiveness and caregiver engagement reflect acceptability; and resource-sensitive counselling reflects the perceived appropriateness of intervention messages within household food realities. Adjustments in communication, alignment of counselling with locally available resources, and reorganization of delivery processes further illustrate how implementation can remain responsive while preserving core intent [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. These patterns reinforce that implementation strategies operate within broader socio-ecological conditions [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. For implementation practice, this underscores the need to design interventions that clearly distinguish core functions from adaptable delivery forms, while equipping frontline workers with context-sensitive strategies such as flexible scheduling, follow-up mechanisms, and community-supported engagement.\u003c/p\u003e \u003cp\u003eSupportive supervision emerged as a central mechanism through which adaptive delivery and fidelity were aligned over time. Rather than functioning solely as a monitoring tool, supervision provided a structured platform for reflection, feedback, and guided adjustment. Through this process, observed delivery challenges were reviewed and used to inform subsequent adjustments in delivery practices. This is consistent with evidence from community health systems where supervision supports learning and quality improvement [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] and facilitates alignment of delivery practices in CHW programs [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. For policy and health systems strengthening, these findings point to the need to invest in supervision models that integrate real-time feedback, problem-solving, and decision support, rather than relying on compliance-oriented supervision alone.\u003c/p\u003e \u003cp\u003eThe present study provides a process-oriented perspective on how fidelity and adaptation can be managed during routine implementation. The observed pattern ‒ where implementation experiences inform reflection, leading to bounded adaptations that preserve core intervention functions ‒ supports a core functions/forms interpretation of fidelity and adaptation. Delivery forms were adjusted to fit contextual realities while core intervention components remained consistent across implementation. The longitudinal nature of this process further indicates that alignment between adaptation and fidelity evolves over time, rather than being achieved at a single point [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. For research, this underscores the value of longitudinal and mixed-methods approaches that capture how implementation processes unfold, and highlights the need for analytic frameworks that explicitly examine interactions between context, supervision, adaptation, and fidelity in real-world settings.\u003c/p\u003e \u003cdiv id=\"Sec25\" class=\"Section2\"\u003e \u003ch2\u003eStudy strengths and limitations\u003c/h2\u003e \u003cp\u003eThis study has several strengths. The longitudinal mixed-methods design enabled examination of how adaptive implementation and fidelity evolve over time, addressing a key gap in implementation research that often relies on cross-sectional or single-time-point assessments. The integration of quantitative fidelity measures with qualitative data from CHWs, adolescents, and caregivers strengthened the credibility of findings and enabled in-depth understanding of how delivery processes, adaptive strategies, and observed fidelity patterns operated as interrelated processes. Fidelity assessment data were collected prospectively across implementation periods, rather than relying on retrospective accounts. Embedding the study within routine CHW delivery systems further enhances the relevance and applicability of the findings to real-world implementation contexts.\u003c/p\u003e \u003cp\u003eHowever, fidelity assessments were based on periodic rather than continuous observations and may not have captured all session-level variation; this was mitigated through repeated observations across early, mid, and late implementation and triangulation with qualitative data. Fidelity observations were conducted by supervisors involved in implementation, which may have introduced observer or social desirability bias; standardized checklists and unannounced visits were used to minimize this risk. Although qualitative data were collected repeatedly, FGDs with adolescents and parents involved different participants across rounds; thus, observed changes reflect evolving implementation experiences across groups rather than individual-level change. This was addressed through purposive sampling and triangulation across CHWs, adolescents, and parents. Because adaptations were identified through qualitative accounts and supervision-linked interpretation, the study cannot attribute observed fidelity changes to specific adaptations, nor estimate independent effects of adaptive strategies on fidelity outcomes, instead providing an integrated longitudinal account of supervision, adaptation, and fidelity.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study provides empirical evidence that adaptive delivery and implementation fidelity are best conceptualized as interdependent implementation processes rather than competing priorities. In this CHW-led adolescent nutrition intervention, fidelity monitoring, supportive supervision, and guided problem-solving supported a feedback process through which delivery adaptations were made while maintaining core intervention functions. These findings highlight the value of structured supervision systems in guiding bounded adaptation and sustaining fidelity in routine community health delivery.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eTrial registrations:\u0026nbsp;\u003c/strong\u003eThe parent randomized controlled trial was prospectively registered with the Pan African Clinical Trials Registry \u003cem\u003e(PACTR202501305580883)\u0026nbsp;\u003c/em\u003eon 7\u003csup\u003e\u0026nbsp;\u003c/sup\u003eJune 2024\u003cem\u003e.\u003c/em\u003e https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=30558\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study, part of the ARISE-NUTRINT (Africa Research, Implementation Science, and Education \u0026ndash; Reducing nutrition-related NCDs in adolescence and youth) project, was conducted in accordance with the Declaration of Helsinki. Ethical approval was obtained from the Research and Ethics Committee at MakSPH (Ref: SPH-2023-460), and the study was registered with the Uganda National Council for Science and Technology (Ref: HS3481ES).\u003c/p\u003e\n\u003cp\u003eWritten informed consent was obtained from all adult participants (AYAs aged 18\u0026ndash;24 years, parents or guardians, and CHWs). For adolescents aged 10\u0026ndash;17 years, written informed consent was obtained from their parents or guardians, and assent from the adolescents. Participation was voluntary, and participants could withdraw at any time without consequence.\u003c/p\u003e\n\u003cp\u003eAudio recordings and translated data were stored on password-protected, encrypted devices accessible only to the research team.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe de-identified quantitative fidelity dataset supporting the findings of this study is provided as \u003cstrong\u003eSupplementary Material 3\u003c/strong\u003e. Excerpts from qualitative transcripts sufficient to support the analytic claims are presented in the manuscript. Full de-identified qualitative transcripts are not publicly available due to ethical and confidentiality considerations but may be made available from the corresponding author on reasonable request, subject to applicable ethics and data protection requirements.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was conducted as part of the ARISE-NUTRINT project, a collaborative project between MakSPH in Uganda, and 13 other institutions in Africa, Europe and the Harvard\u0026nbsp;School of Public Health in the United States of America. The project is funded by the European Union under Project Grant Number 101095616. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. Funding acquisition at MakSPH was led by DG and JB, Co-investigators on the ARISE-NUTRINT project.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConceptualization: TBu and RN; Data curation: TBu; Formal analysis: TBu; Funding acquisition: DG and JB; Investigation: TBu; Methodology: TBu, RN, EB, and SL; Validation: TBu; Visualization: TBu; Writing original draft: TBu; Review and Editing revised manuscript: TBu, EB, SL, JB, MMS, TB\u0026auml;, DG, and RN.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor details\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003csup\u003e1\u003c/sup\u003e\u003c/strong\u003eDepartment of Epidemiology and Biostatistics, School of Public Health, Makerere University, Kampala, Uganda\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003csup\u003e2\u003c/sup\u003e\u003c/strong\u003eIowa State University-Uganda Program, Center for Sustainable Rural Livelihoods.\u0026nbsp;P.O. Box 218 Kamuli, Uganda\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e3\u003c/sup\u003eDepartment of Community Health and Behavioural Sciences, School of Public Health, Makerere University, Kampala, Uganda\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e4\u003c/sup\u003eDepartment of Public Health and Nutrition, Faculty of Health Sciences, Victoria University, Kampala, Uganda.\u0026nbsp;\u003cbr\u003e\u003csup\u003e5\u003c/sup\u003eDepartment of Psychiatry and Psychotherapy (Campus Charit\u0026eacute; Mitte), Charit\u0026eacute; \u0026ndash; Universit\u0026auml;tsmedizin, Berlin, Germany.\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e6\u003c/sup\u003eGerman Center for Mental Health (DZPG), Berlin, Germany.\u003cbr\u003e\u0026nbsp;\u003csup\u003e7\u003c/sup\u003eAfrica Academy for Public Health, Dar es Salaam, Tanzania.\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e8\u003c/sup\u003eHeidelberg Institute of Global Health\u0026nbsp;(HIGH), Medical Faculty and University Hospital, Heidelberg University, Heidelberg, Germany.\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e9\u003c/sup\u003eDepartment of Global Health and Population, Harvard T.H. Chan School of Public Health, Harvard University, Boston, USA.\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e10\u003c/sup\u003eAfrica Health Research Institute (AHRI), Somkhele and Durban, South Africa.\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e11\u003c/sup\u003eDepartment of Disease Control and Environmental Health, School of Public Health, Makerere University, Kampala, Uganda.\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e12\u003c/sup\u003eDepartment of Preventive Medicine, College of Medicine, Korea University, Seoul, South Korea\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors acknowledge the German Alliance for Global Health Research (GLOHRA), through PD Dr. Shannon McMahon, for awarding a short training scholarship to the first author to attend a one-week training in qualitative research in global health at the Heidelberg Institute of Global Health, Germany, in October 2024. This training contributed to strengthening the first author\u0026rsquo;s research skills applied in the present study.\u003c/p\u003e\n\u003cp\u003eWe also acknowledge the CHWs for leading the household-level implementation of the intervention, and the AYAs and their parents for their participation in this study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eDas JK, Salam RA, Thornburg KL, Prentice AM, Campisi S, Lassi ZS, Koletzko B, Bhutta ZA. Nutrition in adolescents: physiology, metabolism, and nutritional needs. Ann N Y Acad Sci. 2017;1393(1):21\u0026ndash;33.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShawon MSR, Rouf RR, Jahan E, Hossain FB, Mahmood S, Gupta RD, Islam MI, Al Kibria GM, Islam S. The burden of psychological distress and unhealthy dietary behaviours among 222,401 school-going adolescents from 61 countries. Sci Rep. 2023;13(1):21894.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHavdal HH, Fosse E, Gebremariam MK, Lakerveld J, Arah OA, Stronks K, Lien N. Perceptions of the social and physical environment of adolescents\u0026rsquo; dietary behaviour in neighbourhoods of different socioeconomic position. Appetite. 2021;159:105070.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi L, Sun N, Zhang L, Xu G, Liu J, Hu J, Zhang Z, Lou J, Deng H, Shen Z. Fast food consumption among young adolescents aged 12\u0026ndash;15 years in 54 low-and middle-income countries. Global health action. 2020;13(1):1795438.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAgedew E, Abebe Z, Ayelign A. Exploring barriers to diversified dietary feeding habits among adolescents in the agrarian community, North West Ethiopia. Front Nutr. 2022;9:955391.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHormenu T. 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Public Health Nutr. 2019;22(12):2157\u0026ndash;69.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBuyinza T, Buzigi E, Bukenya J, Mbuliro M, Kiwanuka J, Ndejjo R, Guwatudde D. Association between nutrition literacy and diet quality among adolescents and young adults in the rural district of Mayuge, Eastern Uganda. BMC Public Health. 2025;25(1):1\u0026ndash;13.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBuyinza T, Buzigi E, Kitimbo J, Ssabika G, Mbuliro M, Kiwanuka J, Bukenya J, Guwatudde D, Ndejjo R. Socio-ecological factors influencing dietary behaviours among adolescents and young adults in rural Eastern Uganda: A qualitative study. PLoS ONE. 2025;20(12):e0337797.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNagawa M, Kirabira P, Atuhairwe C, Mugisha T. Socio-Ecological model factors influencing Fruit and Vegetable consumption among Adolescents in Nakawa Division, Kampala Capital City Authority, Uganda. 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Afr Health Sci. 2019;19(3):2784\u0026ndash;97.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLee S, Kasibante S, Eminai A, Wani S, Opii DJ, Levine LD, Kanyike AM. Effectiveness of a community health worker-led education intervention on knowledge, attitude, and antenatal care attendance among pregnant women in Eastern Uganda. J Health Popul Nutr. 2025;44:232.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMusoke D, Gonza J, Ndejjo R, Ottosson A, Ekirapa-Kiracho E. Uganda\u0026rsquo;s village health team program. Health people: Natl community health worker programs Afghanistan Zimbabwe edn Wash DC: USAID 2020:405\u0026ndash;14.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKurniawan A, Ostojic S, Shinde S, Laxy M, Neumann C, Berhane H, Berhane Y, Hoe C, Liu S, Brandt I. Enhancing adolescent and youth health through nutrition fluency in Sub-Saharan Africa: ARISE-NUTRINT initiative. 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The Value Equation: Three complementary propositions for reconciling fidelity and adaptation in evidence-based practice implementation. BMC Health Serv Res. 2019;19(1):868.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCarroll C, Patterson M, Wood S, Booth A, Rick J, Balain S. A conceptual framework for implementation fidelity. Implement Sci. 2007;2:1\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIkendi S. Impact of nutrition education centers on food and nutrition security in Kamuli District, Uganda. Iowa State University; 2019.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKalkan I. The impact of nutrition literacy on the food habits among young adults in Turkey. Nutr Res Pract. 2019;13(4):352\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBlakstad MM, Mosha D, Bellows AL, Canavan CR, Chen JT, Mlalama K, Noor RA, Kinabo J, Masanja H, Fawzi WW. 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Campbell Syst Reviews. 2020;16(2):e1085.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMoore GF, Audrey S, Barker M, Bond L, Bonell C, Hardeman W, Moore L, O\u0026rsquo;Cathain A, Tinati T, Wight D. Process evaluation of complex interventions: Medical Research Council guidance. \u003cem\u003ebmj\u003c/em\u003e 2015, 350.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNilsen P. Making sense of implementation theories, models, and frameworks. Implementation Science 30. edn.: Springer; 2020. pp. 53\u0026ndash;79.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKajungu D, Hirose A, Rutebemberwa E, Pariyo GW, Peterson S, Guwatudde D, Galiwango E, Tusubira V, Kaija J, Nareeba T, et al. Cohort Profile: The Iganga-Mayuge Health and Demographic Surveillance Site, Uganda (IMHDSS, Uganda). Int J Epidemiol. 2020;49(4):1082\u0026ndash;g1082.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDamschroder LJ, Aron DC, Keith RE, Kirsh SR, Alexander JA, Lowery JC. Fostering implementation of health services research findings into practice: a consolidated framework for advancing implementation science. Implement science: IS. 2009;4:50.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBraun V, Clarke V. Using thematic analysis in psychology. Qualitative Res Psychol. 2006;3(2):77\u0026ndash;101.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"implementation-science-communications","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"iscm","sideBox":"Learn more about [Implementation Science Communications](https://implementationsciencecomms.biomedcentral.com)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ISCM/default.aspx","title":"Implementation Science Communications","twitterHandle":"@ImplementSci","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Adaptive delivery, implementation fidelity, community health workers, adolescent nutrition, Consolidated Framework for Implementation Research, implementation research, rural Uganda","lastPublishedDoi":"10.21203/rs.3.rs-9602420/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9602420/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eAdolescents and young adults (AYAs) aged 10\u0026ndash;24 years in sub-Saharan Africa, including Uganda, experience poor diet quality and low nutrition literacy. Community health worker (CHW)\u0026ndash;led interventions offer a promising delivery platform, yet little is known about how implementation unfolds under routine conditions or how adaptive delivery and fidelity interact. This gap limits the design and scale-up of community-based interventions without compromising core components. However, few studies have empirically examined how fidelity monitoring can inform bounded adaptations during implementation. We examined how adaptive delivery and implementation fidelity interacted over time during the nine-month implementation of a CHW-led intervention in Uganda.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThis longitudinal mixed-methods implementation study was nested within a nine-month randomized controlled trial of a CHW-led adolescent nutrition education intervention in rural Eastern Uganda. Fidelity assessment was based on Carroll\u0026rsquo;s framework, and data were collected prospectively during routine delivery across three implementation periods: early, mid, and late. Qualitative data were collected through repeated focus group discussions with CHWs, adolescents, and parents during implementation. Data were analyzed using a hybrid inductive\u0026ndash;deductive approach, with adaptive delivery processes identified inductively and organized using the Consolidated Framework for Implementation Research. Quantitative and qualitative data were integrated to examine how adaptive delivery and implementation fidelity interacted over time.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eImplementation fidelity varied across the nine-month implementation period, with higher levels during mid-implementation and lower levels in early and late periods. Five adaptive delivery processes were identified: negotiating flexible scheduling and revisits; reinforcing and contextualizing complex content to improve comprehension; tailoring dietary counselling to household constraints; applying micro-scheduling to sustain coverage; and leveraging household and community networks for continuity. Fidelity observations and implementation challenges informed supervisory reflection, guiding bounded adaptations in delivery while preserving core intervention components.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eAdaptive delivery and implementation fidelity were dynamically interrelated during the nine-month delivery of the CHW-led adolescent nutrition education intervention under routine conditions. These processes unfolded through continuous reflection and adjustment in response to contextual influences. The findings indicate that adaptive delivery and implementation fidelity are best conceptualized as interdependent implementation processes, with supervision-mediated feedback supporting context-responsive adaptations while maintaining core intervention functions.\u003c/p\u003e","manuscriptTitle":"Balancing adaptive delivery and implementation fidelity over time: a longitudinal mixed-methods study of a community health worker–led adolescent nutrition intervention in Uganda","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-05 02:56:03","doi":"10.21203/rs.3.rs-9602420/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"208552899470204234679945379682579602713","date":"2026-05-15T10:45:41+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"269384673667258420119938057984955103171","date":"2026-05-14T14:08:40+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-05-13T09:38:51+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-05-05T16:38:28+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-05-05T03:31:23+00:00","index":"","fulltext":""},{"type":"submitted","content":"Implementation Science Communications","date":"2026-05-03T20:09:09+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"implementation-science-communications","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"iscm","sideBox":"Learn more about [Implementation Science Communications](https://implementationsciencecomms.biomedcentral.com)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ISCM/default.aspx","title":"Implementation Science Communications","twitterHandle":"@ImplementSci","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"48d9fa7a-9226-44ba-b855-b86c1b4af221","owner":[],"postedDate":"May 5th, 2026","published":true,"recentEditorialEvents":[{"type":"reviewerAgreed","content":"208552899470204234679945379682579602713","date":"2026-05-15T10:45:41+00:00","index":12,"fulltext":""},{"type":"reviewerAgreed","content":"269384673667258420119938057984955103171","date":"2026-05-14T14:08:40+00:00","index":11,"fulltext":""},{"type":"reviewersInvited","content":"5","date":"2026-05-13T09:38:51+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-05-05T16:38:28+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-05-05T03:31:23+00:00","index":"","fulltext":""},{"type":"submitted","content":"Implementation Science Communications","date":"2026-05-03T20:09:09+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-13T09:55:08+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-05 02:56:03","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9602420","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9602420","identity":"rs-9602420","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}