QALYs versus HYEs--what's right and what's wrong. A review of the controversy.

The paper uses an axiomatic approach to the description of individual preferences for health status sequences to resolve the major issues at state in the recent controversy over QALYs versus HYEs. While the HYE accounts for an individual's time preference for health, QALY scores based on the time trade-off method will generally differ from the number of HYEs. HYEs do not represent preferences for health under risk unless the utility function for reference flows of health is linear. Collapsing the two-step HYE assessment procedure into a single step entails a loss of information as regards the utility of a health status sequence. Although the procedure does represent preferences for health, it fails to supply a description in terms of HYEs in the case of risk. As a remedy, a modified HYE approach is proposed.