The long‐term effects of primary school‐based obesity prevention interventions in children: A systematic review and meta‐analysis

INTRODUCTION: This systematic review and meta‐analysis investigate the long‐term effects of primary school‐based obesity prevention interventions on body‐mass index (and z‐scores), waist circumference (and z‐scores) and weight status. METHODS: Four databases were searched for studies from date of inception until June 8th, 2021. We included randomized controlled trials (RCT) and non‐RCTs investigating effects ≥12 months post‐intervention of primary school‐based interventions with intervention duration ≥6 months and containing a diet and/or physical activity component on outcomes of interest. Articles were assessed on risk of bias and methodological quality by RoB2 and ROBINS‐I. Meta‐analysis was performed and results were narratively summarized. Evidence quality was assessed with GRADE. RESULTS: Nineteen studies were included, 9 were pooled in a meta‐analysis. No long‐term effects were found on body‐mass index (+0.06 kg/m(2); CI95% = −0.38, 0.50; I (2) = 66%), body‐mass index z‐scores (−0.08; CI95% = −0.20, 0.04; I (2) = 36%), and waist circumference (+0.57 cm; CI95% = −0.62, 1.75; I (2) = 13%). Non‐pooled studies reported mixed findings regarding long‐term effects on body‐mass index, body‐mass index z‐scores and weight status, and no effects on waist circumference and waist circumference z‐scores. Evidence certainty was moderate to very low. DISCUSSION: No clear evidence regarding long‐term effects of primary school‐based interventions on obesity‐related outcomes was found. Recommendations for further research and policy are discussed. Prospero registration ID: CRD42021240446.