Coste-efectividad de un programa de actividad física de tiempo libre para prevenir el sobrepeso y la obesidad en ni？os de 9-10 a？os

objective: to assess the cost-effectiveness a school-based intervention designed to reduce overweight/obesity and other cardiovascular risk factors in children. methods: standard cost effectiveness analysis methods and two perspectives (societal and institutional) were used. a cluster-randomized controlled trial with 10 intervention schools (691 children) and 10 control schools (718 children) was performed. net costs were calculated by subtracting the usual after-school care cost from intervention costs. the effectiveness of the intervention was measured as the reduction in health outcomes compared with the control group. results: the intervention costs totaled 125,469.75€, representing 269.83€/year/child. the usual after-school care was estimated at 844,56€/year/child. intervention children showed a decrease in triceps skinfold thickness (-1.25mm, 95% ci: -1.82 to -0.67; p <.001). intervention children with body mass index (bmi) between the percentiles 25 and 75 showed a decrease in the percentage of body fat (-0.59%; 95% ci: -1.03 to -0.67; p<.001), and those with a bmi>p75 showed a decrease in triceps skinfold thickness (-1.87mm; 95%ci: -3.43 to -0.32; p<.001), and percentage of body fat (-0.67%; 95%ci: -1.32 to -0.01; p<.05). conclusions: this type of after-school program for recreational physical activity to prevent obesity are likely to be a cost-effective use of public funds and warrant careful consideration by policy makers and program planners.