Incorporating feelings related to the uncertainty about future health in utility measurement

Abstract

The cost-effectiveness of health-care interventions is often evaluated using quality-adjusted life years (QALYs) as a measure of outcome. QALYs are valid representations of welfare only under the questionable assumption of additive independence of utility of health states across time periods. Therefore, some alternatives to QALYs have been proposed, among them healthy-year equivalents (HYEs) (Med. Decis. Making 1989; 9(2):142-149) and a semi-separable utility function (SSUF) (J. Health Econ. 2005; 24(1):33-54). This paper shows that HYEs using a single probability-equivalent standard gamble (SG) question measure the same health construct as the SSUF, which uses a series of probability-equivalent SG questions. The underlying assumption is that final health states are independent of initial health states. In contrast to the SSUF, however, HYEs are not bound by this assumption and also avoid propagating bias in the measurement of SG utilities from one question to the next. This paper also shows that both approaches can incorporate feelings related to the uncertainty about future health and capture them by using certainty equivalent questions.