Body Mass Index Trajectories among the Healthy Communities Study Children: Racial/Ethnic and Socioeconomic Disparities in Childhood Obesity

The purpose of this study is to identify statistically distinguishable trajectories of childhood body mass index (BMI), an important indicator of developmental status of children, and to provide a summary description of demographic characteristics of children based on these distinctive trajectories. Using data from the Healthy Communities Study (HCS), a large longitudinal dataset with oversamples of Hispanic and Black children across 130 communities in the USA, a group-based trajectory analysis approach was used to estimate trajectories of children based on their BMI-z scores. The three most distinguishable BMI trajectory groups identified for the HCS children show no marked increase or decrease in standardized BMI over an age range of 2 to 11. Approximately 28.5% of children were in a trajectory group with consistently obese BMI-z scores for their sex and age. The patterns of BMI trajectory groups identified for boys and girls are similar, but BMI-z scores for boys tend to be slightly higher than those for girls. These BMI trajectories are characterized by racial/ethnic and socioeconomic status disparities. Hispanic and Black children were more likely to be in the obese trajectory group than White children. Children with parents having less education, or children from low family income level, were more likely to be in the obese trajectory group than counterpart children. The findings suggest that BMI disparities exist from the early years of childhood and persist across childhood, with higher BMI associated with Black and Hispanic children as well as those from low socioeconomic status backgrounds.