Transforming Obesity Prevention for CHILDren (TOPCHILD) Collaboration: protocol for a systematic review with individual participant data meta-analysis of behavioural interventions for the prevention of early childhood obesity
Authors: Hunter Kylie E , Johnson Brittany J , Askie Lisa , Golley Rebecca K , Baur Louise A , Marschner Ian C , Taylor Rachael W , Wolfenden Luke , Wood Charles T , Mihrshahi Seema , Hayes Alison J , Rissel Chris , Robledo Kristy P , O'Connor Denise A , Espinoza David , Staub Lukas P , Chadwick Paul , Taki Sarah , Barba Angie , Libesman Sol , Aberoumand Mason , Smith Wendy A , Sue-See Michelle , Hesketh Kylie D , Thomson Jessica L , Bryant Maria , Paul Ian M , Verbestel Vera , Stough Cathleen Odar , Wen Li Ming , Larsen Junilla K , O'Reilly Sharleen L , Wasser Heather M , Savage Jennifer S , Ong Ken K , Salvy Sarah-Jeanne , Messito Mary Jo , Gross Rachel S , Karssen Levie T , Rasmussen Finn E , Campbell Karen , Linares Ana Maria , Øverby Nina Cecilie , Palacios Cristina , Joshipura Kaumudi J , González Acero Carolina , Lakshman Rajalakshmi , Thompson Amanda L , Maffeis Claudio , Oken Emily , Ghaderi Ata , Campos Rivera Maribel , Pérez-Expósito Ana B , Banna Jinan C , de la Haye Kayla , Goran Michael , Røed Margrethe , Anzman-Frasca Stephanie , Taylor Barry J , Seidler Anna Lene 
Published: January 2022

IntroductionBehavioural interventions in early life appear to show some effect in reducing childhood overweight and obesity. However, uncertainty remains regarding their overall effectiveness, and whether effectiveness differs among key subgroups. These evidence gaps have prompted an increase in very early childhood obesity prevention trials worldwide. Combining the individual participant data (IPD) from these trials will enhance statistical power to determine overall effectiveness and enable examination of individual and trial-level subgroups. We present a protocol for a systematic review with IPD meta-analysis to evaluate the effectiveness of obesity prevention interventions commencing antenatally or in the first year after birth, and to explore whether there are differential effects among key subgroups.Methods and analysisSystematic searches of Medline, Embase, Cochrane Central Register of Controlled Trials, Cumulative Index to Nursing and Allied Health Literature (CINAHL), PsycInfo and trial registries for all ongoing and completed randomised controlled trials evaluating behavioural interventions for the prevention of early childhood obesity have been completed up to March 2021 and will be updated annually to include additional trials. Eligible trialists will be asked to share their IPD; if unavailable, aggregate data will be used where possible. An IPD meta-analysis and a nested prospective meta-analysis will be performed using methodologies recommended by the Cochrane Collaboration. The primary outcome will be body mass index z-score at age 24±6 months using WHO Growth Standards, and effect differences will be explored among prespecified individual and trial-level subgroups. Secondary outcomes include other child weight-related measures, infant feeding, dietary intake, physical activity, sedentary behaviours, sleep, parenting measures and adverse events.Ethics and disseminationApproved by The University of Sydney Human Research Ethics Committee (2020/273) and Flinders University Social and Behavioural Research Ethics Committee (HREC CIA2133-1). Results will be relevant to clinicians, child health services, researchers, policy-makers and families, and will be disseminated via publications, presentations and media releases.PROSPERO registration numberCRD42020177408.