Evaluating school-based obesity prevention interventions in 6- to 12-year-old children: a scoping review of all reported outcomes and expert consultation

Introduction: This scoping review aims to identify all outcomes reported in school‐based obesity prevention interventions in childhood. It serves as an essential first step towards developing an internationally agreed‐upon Core Outcome Set (COS), which defines what should be measured in all school‐based childhood obesity prevention studies, thereby reducing research waste and enhancing the comparability and relevance of future research. Methods: Four databases (PubMed, Embase, Cochrane Database of Systematic Reviews, and PsycINFO) were searched for published studies on controlled trials of school‐based overweight/obesity prevention interventions in 6‐ to 12‐year‐olds, from inception until June 2024. Two researchers independently searched for relevant articles, extracted study/intervention characteristics, and reported outcomes. Through multiple meetings and feedback rounds, an international expert panel, including researchers (n = 5), healthcare providers (n = 4; i.e., pediatrician, youth health physician, dietician, psychologist), and a health educator identified unique outcomes underlying all reported outcomes, by reflecting on what was measured irrespective of how outcomes were defined and measured. Results: In total, 262 published studies that evaluated 242 interventions were included in this review. From these studies, we extracted 642 different reported outcomes. BMI (kg/m2) was the most frequently reported outcome (128 studies), then BMI‐z (108 studies) and BMI categories (100 studies). Experts identified 69 unique outcomes from all reported outcomes. Conclusion: There is substantial heterogeneity in outcomes reported in studies evaluating school‐based overweight/obesity prevention interventions in 6‐ to 12‐year‐olds, limiting a synthesis of evidence in meta‐analyses. This highlights the need for a consensus‐based COS to improve the comparability and relevance of evidence of childhood obesity prevention trials.