Quality-adjusted Life Years, Utility Theory, and Healthy-years Equivalents

Abstract

Decisions about medical treatments and the settings of health programs are not purely technical, but also involve issues of value such as the evaluation of trade-offs between quality of life (morbidity) and quantity of life (mortality). The most commonly used measure of outcome in such cases is the quality-adjusted life year (QALY). The authors show that QALYs, being a health status index, do not stem directly from the individual's utility function and thus only partly reflect the individual's true preferences. This might lead to the choice of the nonpreferred alternative due to the misrepresentation of the individual's preferences. Two examples illustrate this claim. An alternative measure of outcome, the healthy-years equivalent (HYE), is described. This measure stems directly from the individual's utility function and thus fully reflects his/her preferences. It combines outcomes of both morbidity and mortality and thus can serve as common unit of measure for all programs, allowing comparisons across programs. Different ways of measuring the HYE are discussed.

Health utility indices and equity considerations

“…Criticism that decision making based on QALYs may not accurately reflect individual preferences is based on the presumption that ideally a QALY should be a vNM utility. In the interpretation of QALYs as vNM utilities, we abstract from the discussion whether the conditions that equate QALYs and vNM utilities are reasonable and it is simply assumed that the individual preference relations satisfy these conditions (for a critical evaluation of these condition see, for example, Mehrez and Gafni (1989), Loomes ~d McKenzie (1989)). …”

A new axiomatic approach to the evaluation of population health

“…8 Third, it has been argued elsewhere that widely used representations of individual preferences for health (such as QALYs) rely on fairly restrictive assumptions (e.g. Loomes and McKenzie, 1989;Mehrez and Gafni, 1989). Thus, the aim of this paper was to consider a framework in which information on individual preferences over health is not available, either for practical or ethical reasons, but in which sound decisions over the evaluation of population health could still be made.…”

“…They translate into our context two of the most well-known and employed techniques to measure the benefits of health interventions in cost-utility analyses. Those techniques were initially considered as polars, although some of their differences and similar aspects were addressed (e.g., Mehrez and Gafni, 1989;Culyer and Wagstaff, 1993;Gafni et al, 1993;Bleichrodt, 1995). We have seen in this paper that they share a solid common ground.…”

“…Economists, practitioners and social scientists alike have long been concerned with this issue. Attempts to develop appealing measures to evaluate the health of a population abound in the literature (e.g., Pliskin et al, 1980;Torrance, 1986;Mehrez and Gafni, 1989;Wagstaff, 1991;Bleichrodt, 1995Bleichrodt, , 1997 Williams, 1997; Dolan, 1998 The purpose of this paper is to take the axiomatic approach to the evaluation of population health, a somewhat unexplored approach in the health economics literature, in contrast to many other fields in economics. An axiomatic study begins with the specification of a domain of problems, and the formulation of a list of desirable properties (axioms) of solutions for the domain, whereas it ends with (as complete as possible) descriptions of the families of solutions satisfying various combinations of the properties (e.g., Thomson, 2001).…”

“…We shall also single out the so-called linear HYE function, which evaluates population health by means of the unweighted aggregation of healthy years equivalents (HYEs). In doing so, we shall be able to scrutinize further the similarities and differences between these two focal concepts (HYEs and QALYs) in health economics, an aspect that has received considerable attention in the literature (e.g., Mehrez and Gafni, 1989;Culyer and Wagstaff, 1993;Gafni et al, 1993;Bleichrodt, 1995).…”