Estimating utility values for health states of overweight and obese individuals using the SF-36

Objective: To use health-related quality-of-life (HRQoL) data from the Australian 1995 National Health Survey to estimate the impact of obesity (as measured by body mass index or BMI) on utility and quality-adjusted life expectancy (QALE). Method: SF-36 responses from 12,661 individuals in the general population were transformed into utility values using the SF-6D algorithm developed by Brazier and colleagues. Separate regression analyses for males and females were used to examine the impact of BMI and five obesity-related medical conditions (diabetes, coronary heart disease, depression, musculoskeletal disorders, and cancer) on utility. The utility estimates were used to provide indicative estimates of the decrease in QALE associated with being overweight or obese. Results: There was a statistically significant negative relationship between BMI and utility for males and females. For males (females), the marginal effect of a one-unit increase in BMI was associated with a -0.0024 (-0.0034) decrement in utility. Based on these estimates, a non-smoking male (female) aged 40 years who is obese can expect 7.2 (8.7) years less of QALE over their remaining lifetime. Conclusions: Results suggest that BMI is negatively associated with utility. Evaluation of policies designed to prevent or treat obesity should capture HRQoL as an outcome.