On the assessment of preferences for health and duration: Maximal endurable time and better than dead preferences
BACKGROUND: Several studies revealed difficulties with the valuation and analysis of health states deemed worse than dead. These problems may be linked to maximal endurable time (MET) preferences, the phenomenon that for severe states better than dead (BTD), shorter durations are often preferred to longer durations. OBJECTIVE: To test the association between the duration of health states and their valuation. METHODS: A representative sample of 123 Dutch respondents (age range, 18-45 years) valued 5 EQ-5D health states. With a straightforward method using BTD preferences, respondents indicated whether a state of a certain duration is better, equal to, or worse than dead. To validate these BTD preferences, MET preferences (whether a longer duration of a health state is better, equal, or worse than a shorter duration) were collected. RESULTS: BTD and MET preferences were strongly related (P < 0.001). For severe health states, although still judged as better than dead, BTD preferences curved downwards with increasing duration. Such curved BTD patterns occurred in 28% of the respondents, especially for more severe states (P < 0.001). CONCLUSIONS: BTD preferences revealed that the value of moderate and severe states declines with increasing duration, suggesting that health and duration interact. For states worse than dead versus states better than dead, traditional valuation techniques have the drawback that different preference questions are used. Using BTD preferences, however, a single simple preference question can assess states better than dead, as well as states worse than dead.