Body mass index growth in a sample of US children: Repeated measures data analysis of the Minneapolis Children's Blood Pressure Study

Longitudinal assessments of the body mass index (BMI) in children and adole scents are limited. The purpose of the study was to describe the growth pat terns of the BMI in children and young adults. Black and White children of Minneapolis Children's Blood Pressure Study (MCBPS) were 6 to 9 years old a t entry and were followed for 12 years at 19 separate visits. Those with at least five visits (n = 1,302) were included for analysis, using non-linear mixed effects models in conjunction with the Gompertz curve. The growth pa tterns of four sex-ethnic groups were different at three levels: starting l evel (SL) (kg/m(2)), asymptote level (AL) (kg/m(2)), and peak growth age (P GA) (in years). In this context, SL is the average BMI level at age 6, AL i s the average BMI level when growth diminishes. and PGA is the average age at which the rate of growth in the BMI peaks. The SL (16.3 +/- 0.1) for Whi te males was significantly greater than SL in the other three sex-ethnic gr oups, among which there were no significant differences. There was a signif icant ethnic difference in AL between Black females (25.5 +/- 0.3) and Whit e females (24.4 +/- 0.2) and a marginally significant difference in AL betw een Black females and Black males (24.4 +/- 0.3). For PGA, only sex differe nces were significant: Black females reached the peak at the earliest age a t (11.5 +/- 0.1) years, followed by White females (11.7 +/- 0.1), Black mal es (12.6 +/- 0.1), and White males (12.8 +/- 0.1). (C) 2001 Wiley-Liss, Inc .