Co-production as an Emerging Methodology for Developing School-Based Health Interventions with Students Aged 11-16: Systematic Review of Intervention Types, Theories and Processes and Thematic Synthesis of Stakeholders' Experiences.

Co-production affords an intervention's target population the opportunity to participate in intervention theory decision-making during the development process. This addresses the over-reliance on developing interventions through academic theories which can be devoid of contextual understanding and result in challenges to implementing school-based health programmes. There is an emergent empirical literature on co-producing school-based health interventions, but an understanding of appropriate theoretical types and processes and stakeholders' experiences is lacking. Through the conduct of a systematic review, this study seeks to understand the types and underlying theories and processes for co-production in school-based health interventions with students aged 11-16. A thematic synthesis explored stakeholders' experiences of the different types of co-production. A systematic search of five electronic bibliographic databases, citation tracking of included studies, and consultation with an expert international panel were employed. Of 27,433 unique papers, 30 papers representing 22 studies were retained to describe types, and 23 papers of 18 studies used to synthesise stakeholders' experiences. Three types were identified: external, individual-level, and system-level capacity-building. Whilst this review showed variability in co-production types, stakeholders involved and processes, shared functions were identified. Students', school staff, facilitators' and researchers' experiences in terms of acceptability, feasibility and undertaking decision-making are discussed. Recommendations for conceptualising and reporting co-production and process evaluations of co-produced school-based health interventions are highlighted.