I regret that I cannot accept Christopher Chong's “challenge,” which is based on a misinterpretation of my commentary.1 Nowhere did I argue that “because the quality-adjusted life-year (QALY) has ‘severe limitations’ it is not useful for cost-utility analyses.” Of course it is useful. My argument is rather that those severe limitations must be well understood by any decision-makers who would use the QALY in making health policy decisions.
There is no dispute that estimates of utility vary according to how and from what viewpoint they are made. My point is that if such estimates are to be used in health policy decisions, this variability must be understood by the decision-makers. Most decision-makers would probably be astonished to learn that utility is not a constant unit of measurement and that it can only validly be used to compare one health option with another when the health preferences have been estimated by the same method and from the same viewpoint.
As for there being no difference between comparing cost-effectiveness ratios and “using league tables based on number-needed-to-treat to evaluate the clinical effectiveness of interventions,” the issue is again the extent to which the decision-makers understand the units of measurement they are employing. I suspect that clinicians understand the index number-needed-to-treat far better than health care administrators understand utilities and QALYs.
And of course I agree that we should continue to try to develop “an ideal measure incorporating both quantity and quality of life.” But if the imperfect measurements that we have developed up to this time are used in health policy decisions, the imperfections must be acknowledged and understood by the users.
Maurice McGregor McGill University Health Centre Montréal, Que.
Reference
- 1.McGregor M. Cost–utility analysis: use QALYs only with great caution [editorial]. CMAJ 2003; 168 (4):433-4. [PMC free article] [PubMed]