The prevalence of obesity has risen dramatically in the US, but there has been little information about the economic impact of this trend for individual states.

John Cawley, professor of policy analysis and management at Cornell’s College of Human Ecology, recently published research that provides new insights on how individual states are affected by the health-care costs of obesity. The article is published in the January 2018 issue of Clinical Chemistry, which is devoted to the topic of obesity.

“We have, for the first time, estimated the percentage of health-care spending that is devoted to obesity, using microdata for each state,” said Cawley, who co-authored “The Impact of Obesity on Medical Costs and Labor Market Outcomes in the U.S.” with Adam Biener of the Agency for Healthcare Research and Quality and Chad Meyerhoefer of Lehigh University.

Large differences exist across states, Cawley said. “In 2015, states, such as Arizona, California, Florida, New York, and Pennsylvania devoted 5% to 6% of their total medical expenditures to treating obesity-related illness, whereas North Carolina, Ohio, and Wisconsin spent more than twice that—over 12% of all health-care dollars in those states were used to treat obesity-related illness.”

Overall, the authors found the percent of US national medical expenditures devoted to treating obesity-related illness in adults rose from 6.13% in 2001 to 7.91% in 2015, an increase of 29%.

The publication reports results by payer type, including private health insurance companies, Medicare, and Medicaid. “Once again, we find dramatic differences across states in the fraction of Medicaid spending that is devoted to obesity-related illness,” Cawley said. “For example, over 2001-2015, Kentucky and Wisconsin devoted over 20% of their Medicaid spending to obesity-related illness. In contrast, in New York, 10.9% of Medicaid spending was devoted to obesity-related illness, and the average for the US as a whole was 8.23% during that period.”

By analyzing data for 2001-2015 from the Medical Expenditure Panel Survey, a nationally representative survey of Americans’ health-care utilization and costs, the authors estimated the percent of health-care costs that were associated with adult obesity for the most populous states.

Estimates could not be generated for less populous states because of a scarcity of information about their residents in the data. Previous estimates of the health-care costs of obesity by state were not based on microdata for each state, but on assumptions about how national costs should be apportioned to different states.

These differences across states are driven by a number of factors, such as differences in obesity prevalence, health-care access by obese individuals, how obesity is treated, and prices of health care, Cawley said.