Targeting childhood obesity in schools: An examination of the stability and utility of the Value Added Index

摘要

Background High rates of childhood obesity and overweight have promoted interest in school-based interventions. As a way to identify schools with high unexpected prevalence of obesity and the greatest need, Procter and associates developed a 'Value Added Index' (VAI). It compares rates of obesity in entry level and advanced students in elementary schools, quantifying the extent to which rates for advanced students are higher than what would be expected given entry level rates and socio-demographic characteristics. Methods This paper replicates their analysis using data over a 4 year time span from 17 schools in the western United States. Our analysis compared results obtained with the relatively complicated mixed-model approach, which was used by Procter and associates, and a more simple linear regression, which could be easily used by local school officials. Results were also compared across the 4 years for which data were available. Results Identical results were found when the two methods were compared. There was little stability in the rank ordering of schools, based on the VAI, from 1 year to another. Conclusions Our results cast doubts on the utility of the VAI for policy makers and suggest policy makers consider a universalistic, rather than targeted, approach to interventions.