Effect of Time-Varying Exposure to School-Based Health Promotion on Adiposity in Childhood.

BACKGROUND

The results of most school-based health promotion initiatives are inconclusive.

OBJECTIVES

This trial assessed the effect of time-varying exposures to a multicomponent school-based health promotion intervention (SI! Program) on adiposity markers.

METHODS

A total of 48 schools in Madrid (Spain) were cluster randomized to receive the SI! Program through elementary education grades 1 to 6 (E1-6, 12 schools, 459 children), 1 to 3 (E1-3, 12 schools, 513 children), or 4 to 6 (E4-6, 12 schools, 419 children) or to receive the standard curriculum (control, 12 schools, 379 children). The primary endpoint was the between-group difference at 3- and 6-year follow-up in the change from baseline in adiposity markers and the overall knowledge-attitudes-habits (KAH) score.

RESULTS

At 3-year follow-up, children who had the intervention showed significantly lower increases than the control group in z-scores for body mass index (BMI), waist-to-height ratio (WHtR), and waist circumference (WC) (zBMI: -0.09; 95% CI: -0.16 to -0.03; P = 0.003; zWC and zWHtR: -0.19; 95% CI: -0.28 to -0.10; P < 0.001). At 6-year follow-up, the beneficial trend in zWC and zWHtR was maintained in the E1-6 and E1-3 groups: difference zWC control vs E1-6 (-0.19; 95% CI: -0.36 to -0.03; P = 0.020), control vs E1-3 (-0.22; 95% CI: -0.38 to -0.06; P = 0.009); difference zWHtR control vs E1-6 (-0.24; 95% CI: -0.41 to -0.06; P = 0.009), and control vs E1-3 (-0.29; 95% CI: -0.47 to -0.11; P = 0.001). No significant between-group differences were found in the change of overall KAH score.

CONCLUSIONS

Early elementary school interventions may be more effective than later interventions on abdominal adiposity. Further research should assess the sustainability effects of school-based health promotion programs.