Longitudinal assessments of the body mass index (BMI) in children and adolescents are limited. The purpose of the study was to describe the growth patterns 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 at 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 patterns of four sex-ethnic groups were different at three levels: starting level (SL) (kg/m(2)), asymptote level (AL) (kg/m(2)), and peak growth age (PGA) (in years). In this context, SL is the average BMI level at age 6, AL is 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 White males was significantly greater than SL in the other three sex-ethnic groups, among which there were no significant differences. There was a significant ethnic difference in AL between Black females (25.5 +/- 0.3) and White females (24.4 +/- 0.2) and a marginally significant difference in AL between Black females and Black males (24.4 +/- 0.3). For PGA, only sex differences were significant: Black females reached the peak at the earliest age at (11.5 +/- 0.1) years, followed by White females (11.7 +/- 0.1), Black males (12.6 +/- 0.1), and White males (12.8 +/- 0.1).
Copyright 2001 Wiley-Liss, Inc.