Effectiveness of school-based interventions to prevent obesity among children aged 4 to 12 years old in middle-income countries: A systematic review and meta-analysis.

Economic and accompanying nutrition transition in middle-income countries is resulting in rapidly increasing childhood obesity prevalence, exceeding acceleration rates in the West. Previous school-based obesity prevention reviews have mainly included studies from high-income countries. This review aimed to summarize the evidence from randomized controlled trials evaluating the effectiveness of school-based interventions in preventing childhood obesity in middle-income countries. Six electronic databases were searched: MEDLINE, EMBASE, CINAHL Plus, LILACS, IBECS and WPRIM. Eligibility criteria included middle-income country setting, randomized/cluster-randomized controlled trials, children aged 4-12 years and school-based interventions targeting dietary intake and/or physical activity. Twenty-one cluster-randomized controlled trials, conducted in Asia (n = 10), South America (n = 4), North America (n = 4) and the Middle East (n = 3), were included. Fifteen studies reported a significant intervention effect on at least one adiposity-related outcome. Characteristics of effective interventions included combined diet and PA interventions, school teacher-delivery, duration of >8 months, parental involvement, education sessions and school food modifications. The risk of bias in these trials was mixed. The pooled estimate of the odds ratio for obesity in intervention versus control schools (nine studies) was 0.77; 95% CI, 0.63 to 0.94; p = 0.009. In conclusion, there is some evidence to support school-based interventions in preventing childhood obesity in middle-income countries.