Participatory design application in obesity prevention targeting young adults and adolescents: a mixed-methods systematic scoping review protocol
Authors: Willmott Taylor Jade , Mathew Alieena , Luck Eve , Rundle-Thiele Sharyn , Carins Julia , Vincze Lisa , Williams Lauren , Ball Lauren 
Published: March 2022

Abstract
Background
Prevention of obesity is economically and sociologically preferable to treatment, with early intervention key to preventing excess weight gain and obesity. The transition from adolescence to young adulthood is a critical intervention period. An expert-led, top-down model has dominated obesity prevention research and practice with limited success. Participatory design (PD) offers potential in transforming obesity prevention research and practice by delivering bottom-up solutions that young people value and may therefore voluntarily engage with over time. An evidence synthesis of PD application in obesity prevention targeting adolescents and young adults is currently lacking.

Objectives
Report the protocol for a mixed-methods systematic scoping review which aims to integrate and synthesise available evidence on PD application in obesity prevention targeting adolescents and young adults. Specifically, the review will address three research questions:
RQ1: How is PD defined in obesity prevention interventions targeting adolescents and young adults?
RQ2: To what extent is PD applied in obesity preventions interventions targeting adolescents and young adults?
RQ3a: How is the utility of PD evaluated in obesity preventions interventions targeting adolescents and young adults?
RQ3b: What is the utility of PD application in obesity prevention interventions targeting adolescents and young adults?

Methods
This mixed-methods systematic scoping review protocol adheres to the PRISMA-P guidelines and is informed by the PRISMA extension for scoping reviews (PRISMA-ScR). The search strategy and eligibility criteria are informed by the sample, phenomenon of interest, design, evaluation, and research type tool. Eligible studies will be peer-reviewed literature published in English, reporting on PD application in obesity prevention interventions (including intervention development, implementation, and/or evaluation) targeting adolescents and young adults (aged 10–35 years). Study designs will include qualitative, quantitative, and mixed methods. The review will comprise a systematic literature search, eligibility screening, data extraction, quality assessment using the Mixed-Methods Appraisal Tool (MMAT), and data analysis using an iterative narrative evidence synthesis approach. Evidence on PD application will be thematically integrated in terms of who was involved, when they were involved, and how and why they were involved. Further thematic analyses will be conducted according to the MATE taxonomy and the United Kingdom Medical Research Council (UK MRC’s) key functions of process evaluations. The MATE taxonomy classifies PD application in terms of methodology, agent of change, training, and engagement. The MRC describes three functions of process evaluations: implementation, mechanisms of impact, and context. Applying both in the evidence synthesis is intended to provide a more complete picture of PD application. Exploratory analyses will be conducted to assess any potential associations between PD application and effectiveness across key outcomes (weight, physical activity, sedentary time, nutrition and dietary habit, mental health, and sleep) reported within intervention evaluations.

Conclusions
Elucidating PD application is a prerequisite to establishing its utility. Through the location and synthesis of available evidence on PD application in obesity prevention targeting adolescents and young adults, this review will categorise and describe different methods of PD application and explore the utility of PD application including whether any differences may be observed between PD method applied and the effectiveness of obesity prevention interventions. Implications will be delineated from the narrative evidence synthesis to inform future research and advance practice in this context.

Systematic review registration
PROSPERO CRD42021268240