QALYs

Abstract

The QALY is the product of life expectancy (estimated in years) and its quality over that time (estimated in utilities or QOL units). It theoretically enables direct comparison of the costs of obtaining different health outcomes through cost utility analysis (CUA). In this review, we argue that, at present, the problems related to the use of utilities preclude the use of cost per QALY as a major determinant of policy decisions on the acquisition and use of health technologies. Those who use CUA can be divided into (i) those who inform the process of decision making through CUA and (ii) those who make the decisions. The former have no direct budgetary responsibility for the decisions that are taken, while the decision makers must pay for those decisions from their budgets. Use of CUA rests on the assumption that all QALYs are of equivalent value in the eyes of society. However, the value accorded to them varies with circumstances. The utilities or QOL indices required to compute QALYs can be measured in different ways, which give different answers, and have been shown to be unreliable. Thus, the QALY is not sufficiently accurate or reliable to be used by decision makers as a basis for comparison of the costs of different technologies. Until the theoretical and practical problems of determining health preferences are resolved and the methods of their measurement are standardised, it is necessary to estimate the cost effectiveness of health interventions by relating their cost to their primary health outcomes.