Comparison of health state utility estimates from instrument-based and vignette-based methods: a case study in kidney disease.

OBJECTIVE: We take advantage of a rare occurrence when two different studies report on the estimation of quality of life utilities for the same health states to assess convergence of the reported measures. Health state utilities are important inputs into health economic models that estimate the impact of new medical technologies using a common metric of health gain-the quality adjusted life-year. RESULTS: We find low concordance between the two measures which is concerning in that this could have important ramifications for health care decision making based on estimated cost-effectiveness. We explore possible reasons for the discrepancy between the two measures and draw implications for the design of future studies.