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.