A fallacy of the multiplicative QALY model for low-quality weights in students and patients judging hypothetical health states

Objectives: In quality-adjusted life-years (QALY) models, it is customary t o weigh life-years with quality of life via multiplication. As a consequenc e, for positive health states a longer duration has more QALYs than a short er duration (i.e., longer is better). However, we have found that for poor health states, many prefer to live only a limited amount of time (i.e., lon ger is worse). Such preferences are said to be maximum endurable time (MET) . In the present contribution, the following questions are asked: a) How lo w does the utility have to be in order for a MET to arise? and b) Do MET pr eferences occur when patients judge hypothetical health states? Methods and Results: We reanalyzed data from 176 students for the hypotheti cal health states of "living with migraines" and "living with metastasized cancer." For utilities smaller than 0.7 (ranging from 0 to 1), the MET pref erence rate was larger than 50%. High MET preference rates were also found in two new studies on migraine and esophageal cancer patients, who evaluate d hypothetical health states related to their disease. Conclusions: We discuss the interpretation of the MET preferences and the p reference reversal phenomenon. Standard QALY models imply that longer is be tter. However, we find that more often, longer is worse for poorly evaluate d health states, Consider the following question: are 3 years with a weight of 0.3 equally as valuable as 1 year with a weight of 0.9? Our results sug gest that the 3-year period may be less valuable because for poor health, m any will prefer a 1-year over a 3-year period.