Underestimation of Adolescent Obesity.

Background: Previous studies assessing the validity of adolescent self-reported height and weight for estimating obesity prevalence have not accounted for, potential bias due to nonresponse in self-reports. Objectives: The aim of this study was to assess the implications of selective nonresponse in self-reports of height and weight for estimates of adolescent obesity. Methods: The authors analyzed 613 adolescents ages 12-17 years from the 2006-2008 Los Angeles Family and Neighborhood Survey, a longitudinal study of Los Angeles County households with an oversample of poor neighborhoods. Obesity prevalence estimates were compared based ' on (a) self-report, (b) measured height and weight for those who did report, and (c) measured height and weight for those who did report. Results: Among younger teens, measured obesity prevalence was higher for those who did not report height and weight compared with those who did (40% vs. 30%). Consequently, obesity prevalence based on self-reported height and weight underestimated measured prevalence by 12 percentage points (when accounting for nonresponse) versus 9 percentage points (when nonresponse was not accounted for). Results were robust to the choice of difference child growth references. Discussion: Adolescent obesity surveillance and prevention efforts must take into account selective nonresponse for self-reported height and weight, particularly for younger teens. Results should be replicated in a nationally representative sample. [ABSTRACT FROM AUTHOR]