Analyzing screening policies for childhood obesity

摘要

The prevalence of obesity in US school-aged children is not only a public health problem, but an economic and national security issue (＞ 25% of Americans ages 17-24 are unqualified for the military because of their weight). The Institute of Medicine (Ref. 1) report states that clinical trials for treating childhood obesity have been hampered by small sample sizes, poor generalizability, and variable follow up, leading to insufficient evidence for effectiveness of intervention in primary care settings such as the US Preventive Services Task Force 2005. As obesity treatment has improved in the past several years, the USPSTF recommends childhood BMI screening and intervention for obesity starting at age six. The present research work tries to derive optimal screening thresholds for children under 18 years old. Using biennial BMI data from the National Longitudinal Survey of Youth (NLSY) samples, a model has been derived on the basis of Markovian evolution of the probability density function (pdf) of BMI for all U.S. children at ages t = 0,2, ...,18, assuming there is no obesity treatment. By optimizing over the class of biennial threshold policies, every child has his BMI measured every two years and receives treatment whenever his BMI exceeds a gender- and age-based threshold. The impact of treatment is estimated using the pooled analysis of three comprehensive moderate or high-intensity behavioral interventions. The optimal screening problem is formulated as a deterministic dynamic program with an infinite-dimensional state. A simulation model has been also used to compare the performance of the USPSTF policy and the policy derived from the dynamic program. (56 refs.)