Hispanic and black US children's paths to high adolescent obesity prevalence

Abstract

Objective: The study aims to identify the ages contributing most to the development of higher obesity prevalence in the 8th grade (approximately age 14) among Hispanic and black children than among non-Hispanic white children in the United States.

Methods: Using the nationally representative Early Childhood Longitudinal Study (ECLS-K), a sample of 17,420 children in kindergarten in 1999, followed in 1st, 3rd, 5th and 8th grades through 2007, was analysed. First, 'normal', 'overweight' and 'obese' weight-status categories in each grade were assigned from US Centers for Disease Control body mass index percentiles. Second, probabilities of being in each of the three weight-status categories in kindergarten and of transitioning between categories after kindergarten were estimated by logistic regression. These probabilities were then used as parameters of a weight-status trajectory simulation model from which a decomposition analysis was performed.

Results: Obesity prevalence in the 8th grade was equally high among Hispanic (25.0%, 95% confidence interval [CI]: 22.3, 27.8%) and black children (25.1%; 95% CI: 20.9, 29.6%) compared to white children (17.4%; 95% CI: 15.9, 19.0%). As much as 73% of the Hispanic-white 8th grade obesity disparity was generated by 3rd grade and 44% by kindergarten. In contrast, only 15% of the black-white obesity 8th grade disparity was generated by kindergarten, whereas 75% was generated between the 3rd and 8th grades and 53% between the 5th and 8th grades.

Conclusions: Although adolescent obesity is equally prevalent among Hispanic and black children, obesity emerges and is sustained earlier in Hispanic children. Diagnosis and prevention strategies should be designed accordingly.

Figure 1

Obesity prevalence of Hispanic, Black and White children, simulated and observed. CI, confidence interval. Source: Authors’ calculations from the Early Childhood Longitudinal Study, Kindergarten 1999 cohort (ECLS-K). Notes: 95% confidence intervals about the simulated prevalence estimates are indicated by the vertical lines extending above and below the bars. They are computed applying the bootstrap method to the source data.

Figure 2

Hispanic and black children’s 8th grade obesity prevalence after successively eliminating their differences from white children’s kindergarten weight-status distributions and from white children’s subsequent weight-status transition probabilities. Source: Authors’ calculations from the Early Childhood Longitudinal Study, Kindergarten 1999 cohort (ECLS-K). Notes: All simulations employ a Markov model to estimate the prevalence of obesity in 8th grade (equation 1 in the text). Simulation (1) retains the minority (Hispanic or black) racial/ethnic group’s kindergarten weight-status distribution and weight-status transition probabilities, producing their simulated 8th grade obesity prevalence shown in Fig. 1; Simulation (2) substitutes in the kindergarten weight-status distribution of white children; Simulation (3) additionally substitutes in the kindergarten-to-1st grade weight-status transition probabilities of white children; Simulation (4) additionally substitutes in the 1st-to-3rd grade weight-status transition probabilities of white children; Simulation (5) additionally substitutes in the 3rd-to-5th grade weight-status transition probabilities of white children; and Simulation (6) additionally substitutes in the 5th-to-8th grade weight-status transition probabilities of white children, producing white children’s simulated 8th grade obesity.