Each of the elements of a utility assessment strategy-defining and describing health states of interest, identifying subjects, choosing a scaling task, aggregating across subjects, determining reliability and validity-is controversial. The controversy is in part explained by the interdisciplinary nature of the problem; different disciplinary conceptualizations of utility lead to different priorities for methodologic problem solving. Controversy is further explained by widely divergent potential applications of utility assessments, including individual decisions made with and without (or by) an agent, and decisions made for populations that may be homogeneous or heterogeneous with regard to utilities for the same health states. Issues can be clarified by focusing on the purpose of the utility assessment and, in the case of clinical decision making, on the most relevant disease-specific outcomes. The prostatectomy decision is an example. Although questions of measurement validity need continuing attention, more attention should be paid to validating uses of utility assessments: Can utility assessments distinguish prospectively, among patients who subsequently experience the same health outcome, those for whom it is associated with a high or low level of well-being? Can utility assessments be used to predict behavior? Can a decision process that includes utility assessments affect decisions in a manner that improves overall well-being? Approaches to such questions are complicated by changes in utilities over time, departures from the normative model of decision making, the effects of decision-making responsibility, and biases introduced by the decision-making process.
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