have had time to adapt to their condition and as a result may value these states more favorably than those who have not experienced them. Whose evaluations of disabilities should be used? Different ethnic and other population subgroups may also evaluate health states differently. Careful comparison of different summary measures is needed to determine just how much variation in summary measures is caused by different choices about weighting health states. This will help in developing advice about whether and how to use particular measures.
Workshop participants suggested that for clarity, discussions of the ethical status of summary measures of population health have to distinguish between the preferences (weights assigned to different health states as determined in sample surveys) that are used to construct a measure and the cultural, moral, and other values that guide policymakers in making decisions. Preference weights, of course, involve value judgments, and the methods for incorporating preferences into summary measures are likewise value-laden. These values need to be made explicit.
In addition to choices about assigning weights to different health states, other value judgments also characterize different summary measures. Though most QALY-type measures value a year of healthy life at each age equally, the DALY, as currently constructed, has weighted the value of health at different ages differently, for example, applying lower weights for the very young and the very old. This feature is not an essential element of the general DALY approach, but it is a highly controversial choice that may affect the public acceptability of the measure. Similarly, as Brock notes (1997), value judgments influence choices about which life expectancies to use as a baseline in constructing DALYs because these expectancies differ by gender and other population subgroups, as well as across nations. In any case, the value judgments embedded in the construction of specific summary measures of population health must be made evident if these measures are to be responsibly used or revised for such purposes as resource allocation.
Additional ethical controversies about both the design and the application of summary measures arise when they are employed in cost-effectiveness analyses that are intended to guide resource allocation at the population level. These controversies involve a particularly difficult set of distributive issues that are intrinsic to decisions about resource allocation regardless of the data and measures used to inform the decisions. When should resources be allocated to produce “best outcomes” and when resources should be divided to give people fair chances at some benefit? How much priority should the sickest or worst-off patients have? When should the prospect of modest benefits to many people outweigh the delivery of significant benefits to fewer people?
The straightforward use of cost-effectiveness analysis favors specific, yet contested, answers to these questions (Harris, 1987). That is, it would give no priority to the sickest patients, would permit any aggregation that maximized health benefit per dollar spent, and would always support the best outcomes. The contested ethical assumptions behind this approach to cost-effectiveness analysis are that a unit of a summary measure—be it a QALY or a DALY— has the same moral value wherever it is distributed, that a benefit to one always compensates for a loss to another, and that it is always morally desirable to maximize benefit in the aggregate or at the margin. Thus, for example, a loss of one quality-adjusted life year for a single person can be offset by a gain of a twentieth of a quality-adjusted life year for 20 different people. These assumptions, as Rawls (1971) argues, ignore the “separateness” of persons (i.e., that the losers and the gainers are different people with different experiences not reflected in theoretical assumptions).