Analysing risk attitudes to time

Abstract

The assumption of risk neutrality over discounted life years underlies the standard QALY model of individual preferences over health outcomes, and is thus implicitly assumed by NICE and other health technology advisory bodies worldwide. The primary objective of this article is to report a study to test the assumption in a convenience sample of 30 respondents with use of the probability equivalence version of the standard gamble. The results indicate considerable risk aversion over life years, and therefore call into question the standard assumption of risk neutrality in practical cost-utility analyses (CUA). A secondary objective is to observe whether risk aversion can be reduced through the use of the lottery equivalents method, under the hypothesis that the gambling effect can be lessened with this instrument. In a separate convenience sample of 40 respondents, however, the observed level of risk aversion was at least that seen in the standard gamble. Further research is warranted to ascertain whether risk aversion over discounted life years is a generalisable concern