Relationship between prevalence of childhood obesity in 17-year-olds and socioeconomic and environmental factors: prefecture-level analysis in Japan.

To investigate the association between childhood obesity and neighborhood-level socio-economic and environmental factors in Japan. The prevalence of childhood obesity in 2008 was obtained from annual reports of the School Health Survey. The following 12 factors were publicly available: income per person, ratio of people completing up to college or university education, population density, total length of roads per square kilometer, number relative to the population of food and drink stores, restaurants, large-scale retail stores, convenience stores, passenger cars, traffic accidents, criminal offenses, and death by accidents. The ratio of people completing up to college or university education was inversely associated with obesity in boys and girls. No association was found between obesity and the other factors examined. An inverse association was shown between educational level and childhood obesity in both boys and girls. Further studies integrating associations between childhood obesity and neighborhood-level factors are needed.