A FALLACY OF THE MULTIPLICATIVE QALY MODEL FOR LOW-QUALITY WEIGHTS IN STUDENTS AND PATIENTS JUDGING HYPOTHETICAL HEALTH STATES

Abstract

Objectives: In quality-adjusted life-years (QALY) models, it is customary to weigh life-years with quality of life via multiplication. As a consequence, for positive health states a longer duration has more QALYs than a shorter 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., longer is worse). Such preferences are said to be maximum endurable time (MET). In the present contribution, the following questions are asked: a) How low does the utility have to be in order for a MET to arise? and b) Do MET preferences occur when patients judge hypothetical health states?

Methods and Results: We reanalyzed data from 176 students for the hypothetical health states of “living with migraines” and “living with metastasized cancer.” For utilities smaller than 0.7 (ranging from 0 to 1), the MET preference rate was larger than 50%. High MET preference rates were also found in two new studies on migraine and esophageal cancer patients, who evaluated hypothetical health states related to their disease.

Conclusions: We discuss the interpretation of the MET preferences and the preference reversal phenomenon. Standard QALY models imply that longer is better. However, we find that more often, longer is worse for poorly evaluated 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 suggest that the 3-year period may be less valuable because for poor health, many will prefer a 1-year over a 3-year period.