Using concentration index to study changes in socio-economic inequality of overweight among US adolescents between 1971 and 2002

Background: The prevalence of overweight among adolescents continues to increase in the United States. This study examines the changes in socio-economic status (SES) inequality of overweight among US adolescents in the past three decades. Methods: Concentration Index (CI) was utilized to measure changes in the SES inequality in prevalence of overweight among US adolescents. Data collected from 15 286 adolescents in four waves of the National Health and Nutrition Examination Surveys (NHANES) between 1971 and 2002 and Hispanic Health and Nutrition Examination Survey (HHANES) (1982-84) were used. Results: Changes in the SES inequality of overweight among US adolescents and considerable gender and ethnic differences were detected. For boys, CI varied from 0.04 in NHANES I to -0.04 in NHANES 1999-2002; for girls, CI varied from -0.12 in NHANES I to -0.18 in NHANES III. Among whites, SES disparity peaked in NHANES III and declined thereafter. Patterns in black and Mexican-American adolescents were mixed. Conclusions: Patterns of SES disparity of overweight among US adolescents varied across ethnic and gender groups, and have changed over time. Disparities have decreased since the early 1990s with the rise of the obesity epidemic. Obesity prevention and management efforts should target all SES groups in the United States.