Evaluating quality-adjusted life years: Estimation of the Health Utility Index (HUI2) from the SF-36

Quality-adjusted life years (QALYs) are well recognized as a valid measure for outcomes in cost-effectiveness analyses. A summary health utility score is necessary to evaluate QALYs. The objective of this study was to predict a summary utility score (represented by the Health Utility Index [HUI2]) f rom scores on the SF-36. Methods. A structural equation framework was appli ed to longitudinal data collected from 1992 to 1995 on a sample of patients insured by Southern California Kaiser Permanente (N = 6921). An ordinary l east squares (OLS) method was used to estimate the HUI2. Results. The OLS m odel on cross-sectional data predicted 50.5% of the observed variance in HU I2 scores. Parameter estimates of all SF-36 components showed statistical s ignificance at the P < 0.05 level. Conclusions. Results of this study provi de a quantitative link between two important measures of health status. The present model can be used to estimate health utility summary scores in stu dies that have collected SF-36 data.