Assessing screening policies for childhood obesity

Abstract

To address growing concerns over childhood obesity, the United States Preventive Services Task Force (USPSTF) recently recommended that children undergo obesity screening beginning at age 6. An Expert Committee recommends starting at age 2. Analysis is needed to assess these recommendations and investigate whether there are better alternatives. We model the age- and sex-specific population-wide distribution of BMI through age 18 using National Longitudinal Survey of Youth (NLSY) data. The impact of treatment on BMI is estimated using the targeted systematic review performed to aid the USPSTF. The prevalence of hypertension and diabetes at age 40 are estimated from the Panel Study of Income Dynamics (PSID). We fix the screening interval at 2 years, and derive the age- and sex-dependent BMI thresholds that minimize adult disease prevalence, subject to referring a specified percentage of children for treatment yearly. We compare this optimal biennial policy to biennial versions of the USPSTF and Expert Committee recommendations. Compared to the USPSTF recommendation, the optimal policy reduces adult disease prevalence by 3% in relative terms (the absolute reductions are <1%) at the same treatment referral rate, or achieves the same disease prevalence at a 28% reduction in treatment referral rate. If compared to the Expert Committee recommendation, the reductions change to 6 and 40%, respectively. The optimal policy treats mostly 16-year olds and few children under age 14. Our results suggest that adult disease is minimized by focusing childhood obesity screening and treatment on older adolescents.

Figure 1. Performance of Policies

Tradeoff curve of disease prevalence at age 40 vs. percentage of children ages 2.4,…,16 that are referred for treatment each year, for the optimal biennial screening policy, under 50% compliance (- - -) and 100% compliance (—). The “+” and “×” denote the biennial version of the USPSTF recommendation under 50% and 100% compliance, respectively, and the “◊” and “○” denote the biennial Expert Committee policy under 50% and 100% compliance, respectively. (a) hypertension among males; (b) diabetes among males; (c) hypertension among females; and (d) diabetes among females.

Figure 2. Optimal Screening Thresholds

Optimal screening thresholds for the three-age screening policy at ages (12,14,16), expressed as the percentile of the sex- and age-based BMI distributions tabulated by the CDC (Kuczmarski et al. 2000), for two cases: the percentage of children referred for treatment equals that of the biennial USPSTF policy (— for males and -×- for females) and the disease prevalence equals that of the biennial USPSTF policy (… for males and·×·for females). The biennial USPSTF policy uses the 95^th percentile for ages 6,…,16.