Assessing the Influence of Gestalt-TypeCharacteristics on Preferences OverLifetime Health Profiles

摘要

Introduction. In contrast to the basic tenets of economic theory, there is substantial evidence that people's remembered and predicted utility of events systematically differs from the utility that they experience. These systematic differences are caused by "gestalt characteristics." The objective of this study was to test whether people maximize quality-adjusted life years (QALYs), or whether QALY maximization is compromised by their being influenced by factors that resemble the gestalt characteristics when choosing between lifetime health profiles. Methods. Time trade-off values were elicited from 50 respondents, who were also presented with a series of hypothetical questions that each depicted 2 lifetime health profiles. The respondents were asked to choose which of the 2 profiles in each question they would prefer to experience. By inputting the values that the respondents placed on the health states into the lifetime health profiles, it was possible to observe whether their answers were consistent with QALY maximization or with various hypothesized gestalt-type effects. Results. Across decisions that involve a simple trade-off between the length of life and the quality of thehealth state, choices consistent with QALY maximizing were relatively common, although even here approximately half of the respondents violated this rule. Consistency with QALY maximization was lower in most of the other tests and indicated that many people might, for example, prefer to trade off some lifetime health to experience a good end to life, or to avoid highly unstable lifetime health profiles. Conclusion. The respondents' answers were often consistent with the hypothesized gestalt-type effects, but it is probable that for some of the questions the characteristics themselves were not driving the respondents' answers and that factors such as complex rates of discounting might have played a role. However, whatever the driving motivation behind the respondents' answers, the important point to note from this study is that QALY maximization is often substantially and systematically violated when people are offered a choice over the lifetime health profiles that they would prefer to experience.