BMI, health behaviors, and quality of life in children and adolescents: a school-based study.

OBJECTIVE: To explore the relationship between weight status (BMI) and health-related quality of life in children and adolescents through application of the Child Health Utility 9D, a new generic preference-based instrument. METHODS: Data were collected from primary and high school students in rural and metropolitan regions of South Australia. Consenting participants (2588 in grades 4-6 and 765 in grades 9-10) were weighed and measured and categorized as underweight, healthy weight, overweight, or obese according to International Obesity Taskforce BMI cutoff points (primary outcome). Participants also completed a questionnaire including the Child Health Utility 9D and standardized measures of physical activity, sedentary behavior, sleep patterns, and eating behavior (secondary outcomes). Descriptive and multivariate linear regression analyses were undertaken to calculate mean utility differences. RESULTS: In comparison with healthy-weight primary school students, adjusted mean utilities were lower for overweight (-0.016, P = .02) or obese (-0.039, P = .001) students. For high school students, the adjusted mean utilities were also lower for overweight and obese students but were nonsignificant (-0.018, P > .10). Physical activity, sedentary behavior, sleep patterns, and eating behavior were all found to be significantly associated with utilities. CONCLUSIONS: Irrespective of BMI, young people engaging in more physical activities or less sedentary behavior, and having healthier sleep patterns or eating behavior exhibited higher utilities. Associations between utilities and sleep patterns or eating behavior were stronger than the associations with BMI. Future economic evaluations for obesity interventions should more formally investigate the relationship between changes over time in weight status and health-related quality of life for children and adolescents.