Health state valuation methods and reference points: the case of tinnitus

Many studies support the finding that patients, compared to the general public, valuate a given health condition differently. Based on Prospect Theory, this difference can be explained by adaptation processes resulting in differences in individual reference points. Using tinnitus as a case in point, our objective is to analyze empirically to what extent differences in risk attitudes (as a proxy to reference points) mediate differences in health valuations.

Two hundred ten tinnitus patients and a similar number of unaffected persons indicated their willingness to undergo, hypothetically, an intervention (surgery or treatment) that would either improve or worsen the condition, thus revealing their risk attitudes. Utilities were elicited using three different methods: visual analogue scale (VAS), time trade-off (TTO), and standard gamble (SG). Repeated measure analysis of variance was used to test for mediation of utility differences by reference points.

Health status (affected-unaffected) has a significant effect on tinnitus utilities and risk attitude; at the same time, the latter is significantly associated with utilities. Adjusting for risk attitude, differences by health status disappear for SG and TTO, and are alleviated for VAS.

Reference points in terms of risk attitudes are a potential confounder in the valuation of health states. Taking into account theoretical predictions and issues in measuring SG, TTO, and risk attitudes, these results cast doubt on the construct validity of SG and TTO, and point to the need to recognize and further clarify the role of reference points in health valuation research.