Acceptability, feasibility and program outcomes of an equity-focused, adapted communitybased healthy lifestyle program for children, young people and their families in Perth, Western Australia: An implementation hybrid research protocol. Short title for running header: Community Healthy Lifestyle Program Protocol

Stephanie Smith^1,2,3*Stephen Paull^1,2,3Katie M Iwanowski^1,2,3Tania Harris⁴Joanna C Moullin¹Monica Jane¹Jordan Bill²Deborah A Kerr¹Christina Mary Pollard¹Glenn Pearson³Melanie Robinson²Bonnie J Furzer^3,5,6Natasha Bear⁷Ben Jackson^3,5Robyn Mildon⁸Nick Sevdalis⁹Richard Norman¹Jacqueline A Curran^10,3Cameron C Grant¹¹Sarah C Armstrong^12,13Yvonne C Anderson^1,11,2,3

• ¹Curtin University, Bentley, Australia
• ²Child and Adolescent Health Service, Nedlands, Western Australia, Australia
• ³The Kids Research Institute Australia, Nedlands, Australia
• ⁴Health Consumers' Council, Perth, Australia
• ⁵University of Western Australia, Perth, Western Australia, Australia
• ⁶Thriving in Motion, Perth, Australia
• ⁷Notre Dame University, Perth, Australia
• ⁸Centre for Evidence and Implementation, Melbourne, Australia
• ⁹National University of Singapore, Singapore, Singapore
• ¹⁰Perth Children's Hospital, Perth, Western Australia, Australia
• ¹¹The University of Auckland, Auckland, Auckland, New Zealand
• ¹²Duke University, Durham, North Carolina, United States
• ¹³Duke Center for Childhood Obesity Research, Durham, United States

Background: International guidelines recommend multidisciplinary intervention programs for addressing childhood obesity. In Western Australia, community-based healthy lifestyle programs for children and young people are insufficient for demand, especially for those over-represented in obesity statistics relating to prevalence. This protocol outlines the implementation and evaluation of an adapted, evidenced, community-based program in Perth, Western Australia. Methods: Multiple-methods hybrid research, testing acceptability and feasibility of program scale-out and program participant outcomes. Study (1) Develop the adapted healthy lifestyle program with key partners and Aboriginal and Torres Strait Islander advisors for scale-out. Apply implementation strategies for program realisation, identify critical elements and outcomes to demonstrate program success, and cultural and place-based considerations for program acceptability. Study (2) Assess acceptability, appropriateness, feasibility and local clinical outcomes of adapted healthy lifestyle program pilot. Evaluate the program with children and young people aged 4-16 years with obesity or overweight and weight-related comorbidities, seeking healthy lifestyle change. Weight-related assessments at baseline, 6- and 12-months with weekly sessions for 6 months (estimated n=245 over 22 months, accounting for 30% drop-out). Explore program experience via focus groups with children, young people and caregivers (~8-12 weeks post commencement (~50 program participants and caregivers)), ~6 months post commencement (~50 program completers and caregivers)), and evaluation survey (e.g., declined/dropped-out/completed). Engage with key partners to determine program feasibility for scale-up through workshops (~20 participants) and qualitative proformas (~80 respondents). Mixed model regression will be used to assess within-subject change in outcomes over time. Child health utility instruments will be used for cost-utility analysis. Study (3) Assess program scalability post-pilot. If determined feasible and acceptable, the program will be packaged to assist practitioners and policymakers with scale-up via exploration of currently available packages and key staff interviews. The overarching Replicating Effective Programs framework outlines the implementation stages and the tools and strategies being applied are presented. Qualitative data will be analysed using Framework Analysis. Discussion: Implementation outcomes will be determined by evaluating acceptability, appropriateness and feasibility of scale for this healthy lifestyle program. Utilising implementation science, partnership-building and place-based and cultural considerations, this research will inform potential scale-up of equity-focused healthy lifestyle programs.