Associations Between Health Status and Utilities Implications for Policy
Published in: Medical Care, v. 37, no. 5, May 1999, p. 479-489
Posted on RAND.org on January 01, 2000
BACKGROUND: If shape of a person's utility function is associated with his health status, as is predicted by Prospect Theory, the use of utilities from the healthy could result in 'de facto' discrimination against the sick. OBJECTIVES: To determine if patients' utilities for hypothetical states and for their current health were associated with their health status. DESIGN: A cross-sectional study of the health and values of patients with depressive illnesses. SETTING: Patients from three large primary care practices with various medical illnesses complicated by symptoms of depression. MEASURES: Short-Form 12 health status measurements, standard gamble, and visual analog scale preference measurements for patients' current health and for three hypothetical states. RESULTS: One hundred and forty nine patients enrolled in the study and 139 patients completed the survey. Utilities for the best and worst states were similar across different levels of health status; however, standard gamble utilities for intermediate health states were higher for patients in poorer health than patients in better health (P = 0.019) suggesting utility functions with radically different shapes. Utilities for patients' current health were also associated with their health status. Patients in poor health tended to overvalue their current health relative to the most similar hypothetical state; whereas, patients in good health tended undervalue their current health state (P = 0.036). CONCLUSIONS: In patients with depressive illnesses, there were significant interactions between health and values, that were consistent with the predictions of Prospect Theory, and that could result in systematic under valuation of the health effects of treatments that primarily benefit more severely patients ill.