Evaluating school-based obesity prevention interventions in 6-12-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 toward 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 6-12-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 publised 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 6-12-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.