Moderate and Severe Obesity Have Large Differences in Health Care Costs Tatiana Andreyeva, RAND Graduate School Roland Sturm, RAND Jeanne S. Ringel, RAND

Why look at health care costs across obesity groups? Obesity-related health problems are particularly common among severely obese individuals One would expect commensurate differences in health care costs across obesity groups, yet few data are available The prevalence of severe obesity is increasing at a much faster rate than the spread of obesity

Obesity and Health Status Source: Sturm et al, Health Affairs, March 2004

Obesity and Disability Source: Sturm et al, Health Affairs, March 2004

Severe obesity is increasing at a much faster rate than the spread of obesity Source: Sturm, Arch Internal Med, Oct 2003

Our Approach Estimate the association between obesity and health care utilization and expenditures across varying degrees of obesity – Data from Health and Retirement Study,

Methodology Main dependent variables: –Health care utilization outpatient visits, hospitalization, inpatient days –Total health care expenditures Main explanatory variable: BMI weight class –Normal weight ( ), Overweight (25-30), Moderate obesity (30-35), Severe obesity (35-40), and Extreme obesity (40+) Analyze data cross-sectionally

Model Estimation Results Average predicted health care utilization and costs Adjusted for sociodemographic characteristics and behavioral risk factors By weight class

Obesity and Health Care Costs

Obesity and Health Care Utilization

Limitations Self-reported height and weight underestimate BMI Limited age range of HRS data Excluded institutionalized population Cross-sectional estimates and cannot be interpreted as causal effects

Discussion Widely cited average effects of obesity on health care costs (36-37%) obscure major differences across obesity groups –BMI of is associated with twice the increase in medical expenditures above normal weight (50% increase) than BMI of (25% increase) –BMI of 40+ doubles costs (100% above normal weight) Average estimates will underpredict future health care costs because severe obesity grows at a much faster rate than obesity in general

Conclusion An increasing burden of obesity on the health care system grows disproportionally for the most obese segment of the US population As the prevalence of severe obesity increases at a much faster rate than that of obesity, average estimates of obesity effects obscure real consequences for individuals, hospitals and health plans.

Back up

Model Estimation Log-linear model for health care expenditure data –Better fit the data than alternative models in cross-validation tests –Homogenous smearing transformation Linear model for continuous utilization outcomes (number of doctor visits and hospital days) and a probit model for any inpatient stay Analyze data separately by gender

Obesity and Health Care Costs

Obesity and Health Care Utilization