Simulation of Growth Trajectories of Childhood Obesity into Adulthood

Abstract

Background: Although the current obesity epidemic has been well documented in children and adults, less is known about long-term risks of adult obesity for a given child at his or her present age and weight. We developed a simulation model to estimate the risk of adult obesity at the age of 35 years for the current population of children in the United States.

Methods: We pooled height and weight data from five nationally representative longitudinal studies totaling 176,720 observations from 41,567 children and adults. We simulated growth trajectories across the life course and adjusted for secular trends. We created 1000 virtual populations of 1 million children through the age of 19 years that were representative of the 2016 population of the United States and projected their trajectories in height and weight up to the age of 35 years. Severe obesity was defined as a body-mass index (BMI, the weight in kilograms divided by the square of the height in meters) of 35 or higher in adults and 120% or more of the 95th percentile in children.

Results: Given the current level of childhood obesity, the models predicted that a majority of today's children (57.3%; 95% uncertainly interval [UI], 55.2 to 60.0) will be obese at the age of 35 years, and roughly half of the projected prevalence will occur during childhood. Our simulations indicated that the relative risk of adult obesity increased with age and BMI, from 1.17 (95% UI, 1.09 to 1.29) for overweight 2-year-olds to 3.10 (95% UI, 2.43 to 3.65) for 19-year-olds with severe obesity. For children with severe obesity, the chance they will no longer be obese at the age of 35 years fell from 21.0% (95% UI, 7.3 to 47.3) at the age of 2 years to 6.1% (95% UI, 2.1 to 9.9) at the age of 19 years.

Conclusions: On the basis of our simulation models, childhood obesity and overweight will continue to be a major health problem in the United States. Early development of obesity predicted obesity in adulthood, especially for children who were severely obese. (Funded by the JPB Foundation and others.).

Figure 1:. Predicted Prevalence of BMI Categories to 2030 for Children (A) and Adults (B)

The predicted prevalence of BMI categories from the CHOICES model compared with logistic regression predictions based on NHANES 1999–2014. Severe obesity: BMI ≥ 120% of 95^th percentile (ages 2–17), BMI ≥ 35 (ages 18+)

Figure 2:. Predicted Obesity at Age 35: Prevalence by Year and Cumulative Incidence

A. The predicted prevalence of obesity at age 35 from the simulation model compared to logistic regression predictions from NHANES 1999–2014 for ages 34–36. B. The projected cumulative incidence of obesity for 2-year-olds in 2016.

Figure 3:. Cumulative Incidence of Obesity by Race/Ethnicity

Shaded areas represent 95% uncertainty intervals. This plot shows the projected cumulative incidence of obesity for 2-year-olds in 2016 by race-ethnicity, and indicates that significant disparities are already established at very young ages.

Figure 4:. Predicted Probability of Obesity at Age 35 by Current Age and BMI Category

Shaded areas represent 95% uncertainty intervals. Panel A shows the probability of obesity at age 35 conditional on childhood obesity status. Panel B shows the probability of obesity at age 35 conditional on childhood BMI category.