Overweight among young children in the Philadelphia health care centers: incidence and prevalence.

OBJECTIVES To estimate the prevalence and incidence of overweight among low-income, inner-city children aged 3 to 7 years and to determine predictors of changes in body mass index (BMI) (calculated as weight in kilograms divided by height in meters squared) percentile. DESIGN Retrospective cohort study using administrative and medical records. SETTING The Philadelphia Health Care Centers, 1996 through 2003. PARTICIPANTS Three hundred eighty-six patients who had at least 2 well-child visits between the ages of 3 and 7 years, had at least 1 visit between September 2001 and 2003, and were between the ages of 5 and 7 years at the most recent visit. Mean follow-up time was 2.4 years. MAIN EXPOSURES Age, sex, race/ethnicity, and BMI percentile at baseline. MAIN OUTCOME MEASURES Prevalence and incidence of overweight and at risk of overweight and change in BMI percentile. RESULTS Prevalence of overweight at the initial visit was 18%, with 16% at risk of overweight. At the last visit, the prevalence of overweight was 19%, with 15% at risk of overweight. Based on maximum BMI percentile, 29% were overweight at some point and an additional 19% were at risk of overweight at least once. Annualized incidence of overweight among those not overweight at baseline was 5% per year: 2% per year for normal-weight children and 14% per year for children in the at-risk category. The outcomes were not associated with sex, race/ethnicity, or age at first or last visit. Incident overweight was positively associated with BMI percentile at baseline. CONCLUSION The early onset and frequent persistence of overweight demonstrated herein underline the need to prevent overweight among very young children.