Healthy-years equivalents versus quality-adjusted life years: in pursuit of progress.

The authors respond to the contention that healthy-years equivalents (HYEs) do not fulfil claims they previously made. They refute the argument for the equivalence of the two-stage lottery and the time tradeoff and show that it fails to recognize the difference between choice problems under uncertainty versus certainty. They also dismiss the claim that HYEs assume risk neutrality with respect to healthy years of life, and show that HYEs are superior to the "general" (risk-averse) form of QALYs because HYEs employ fewer assumptions; in particular, they do not assume a specific form of the individual's utility function. The examples they used earlier are demonstrated to be conclusive, and the authors respond to arguments about the practical aspects of using HYEs vs QALYs. Finally, they take issue with the assumption that the roots of the QALY model are all attributable to utility theory.