Objectives: We evaluated the effectiveness and spillover of an after-school health education and physical activity program among Hispanic elementary school children.
Methods: In fall 2008, students in third through fifth grades in 6 schools in El Paso, Texas (n = 901), were randomized to intervention (n = 292 participants) or control (n = 354) classrooms (4 unknown). Intervention classrooms also contained a spillover group (n = 251) that did not join the after-school program but that completed measurements and surveys. The intervention was a 12-week culturally tailored after-school program meeting twice a week. Four-month outcomes were body mass index, aerobic capacity, and dietary intentions and knowledge. We calculated intervention exposure as the proportion of after-school participants per classroom.
Results: Intervention exposure predicted lower body mass index (P = .045), higher aerobic capacity (P = .012), and greater intentions to eat healthy (P = .046) for the classroom at follow-up. Intervention effectiveness increased with increasing proportions of intervention participants in a classroom. Nonparticipants who had classroom contact with program participants experienced health improvements that could reduce their risk of obesity.
Conclusions: Spillover of beneficial intervention effects to nonparticipants is a valuable public health benefit and should be part of program impact assessments.