Summary: Redrawing the US Obesity Landscape: Bias-Corrected Estimates of State-Specific Adult Obesity Prevalence

A CHOICES paper reveals that adult obesity rates in the United States are higher than previously reported by the CDC.

Redrawing the US Obesity Landscape: Bias-Corrected Estimates of State-Specific Adult Obesity Prevalence.
Ward ZJ, Long MW, Resch SC, Gortmaker SL, Cradock AL, Giles C, Hsiao A, Wang YC. 2016. PLoS ONE, 11(3): e0150735.
Abstract & Full text

[Fig 1.] Prevalence of adult obesity (BMI ≥ 30) by state in 2013: Uncorrected vs. Corrected.

[Fig 1.] Prevalence of adult obesity (BMI ≥ 30) by state in 2013: Uncorrected vs. Corrected.

Adult overweight and obesity are among the leading causes of morbidity and mortality in the United States—a problem depicted in the Centers for Disease Control and Prevention’s (CDC) well-known obesity maps. However these figures—which have galvanized state leaders to take action, and have been used to prioritize federal obesity prevention resources—may substantially underestimate the true state-level burden. The data behind these maps rely on self-reported height and weight collected through telephone surveys, yet bias in self-reported measures is well documented and results in underestimates of body mass index (BMI). The CHOICES Project, which created a novel method to correct for this bias, found that as many as 12 million adults with obesity (including 6.7 million with severe obesity) were misclassified by CDC state-level estimates.

“Accurate estimates of state-level obesity are necessary to plan for resources to address this epidemic,” said Zach Ward, lead author and programmer/analyst in the Center for Health Decision Science at the Harvard T.H. Chan School of Public Health. “Our corrected state-level estimates provide decision makers with a more solid foundation of data on which to base obesity prevention policies.”

A closer look at specific states reveals some striking findings. In the adjusted data [Fig. 1], obesity prevalence was below 30 percent in only four states (California, Colorado, Hawaii, and Massachusetts), whereas the CDC maps show most states below this level. Another key finding is that in four states (Arkansas, Mississippi, Tennessee, and West Virginia), the estimated obesity prevalence was over 40 percent—a category not included in any previous CDC data. Also not seen in the existing maps is the prevalence of severe obesity greater than 17.5 percent, now apparent in Alabama, Mississippi, and West Virginia [Fig. 2].

[Fig 2.] Prevalence of adult severe obesity (BMI ≥ 35) by state in 2013: Uncorrected vs. Corrected.

[Fig 2.] Prevalence of adult severe obesity (BMI ≥ 35) by state in 2013: Uncorrected vs. Corrected.

Further, the economic implications of undercounting millions of cases of obesity are large. Assuming incremental obesity-related healthcare costs of $1,000 per individual, undercounting the total 12 million cases of obesity would result in underestimating obesity-related healthcare costs by $12 billion.

These revised maps highlight the need for improved resources to both track and prevent obesity. It is important to note that the Behavioral Risk Factor Surveillance System, on which the CDC maps are based, is the only national BMI surveillance strategy currently in place for gathering state-specific information. These data are crucial, and are what allowed for the adjustments used in this study. Accurate state-specific obesity estimates are necessary to help officials plan appropriately for the medical capacity and economic resources needed to address this epidemic, and institute preventive measures where they are needed most.