A process evaluation to determine the feasibility and acceptability of a peer-led intervention to promote healthy dietary behaviours in the secondary school setting

Background
Adolescents typically consume suboptimal diets increasing the risk of poor health outcomes. School-based, peer-led interventions have shown promise in improving adolescents’ dietary behaviours, albeit studies are limited. Moreover, process evaluations aid in contextualising intervention implementation and outcomes; however, their inclusion in school-based dietary interventions to date remains largely absent. This process evaluation examined the feasibility and acceptability of implementing a school-based, peer-led feasibility pilot intervention to promote healthful dietary behaviours among adolescents in the school canteen setting.

Methods
The feasibility of the intervention was examined via school recruitment, consent, and data collection rates. The acceptability of the intervention among participating pupils, peer-leaders, and school staff was qualitatively assessed. Year 8 pupils (aged 11-12 years) and Year 13 peer-leaders (aged 16-17 years) participated in focus groups, and school staff (n=1 vice principal; n=2 senior teachers; n=3 catering supervisors) participated in one-to-one interviews. Focus groups and interviews were audio-recorded, transcribed, and thematically analysed.

Results
Four schools (n=3 intervention; n=1 control) participated in this study, with 47% of Year 8 pupils (n=227) and their parents/guardians consenting to participate. Data collection measures were feasible, with high questionnaire completion rates at baseline (92%) and endpoint (89%) among the Year 8 pupils. Focus groups (pupils; peer-leaders) and interviews (school staff) indicated a high level of acceptability towards the peer-led intervention. Colour-coded labels at the point of choice, low-cost rewards scheme, and the peer-led approach were particularly well-received intervention components reported among pupils, peer-leaders, and school staff. Key intervention facilitators reported among staff included, namely: feasible time and financial resources required for intervention delivery, non-disruptive to the daily operating of the school and academic studies, and minimal staff/school burden. Common recommendations to enhance future study design among participants included, namely: further interaction with peer-leaders, increased availability of healthy options, utilising an electronic reward scheme (e.g., via cashless canteen systems), and facilitating an online communication system between peer-leaders and the research team.

Conclusions
These findings are relevant to researchers involved in designing dietary interventions within secondary schools. Incorporating process evaluations into intervention study designs provides valuable insights into intervention implementation and outcomes and identifying considerations for larger scale study designs.