Unstable preferences: A shift in valuation or an effect of the elicitationprocedure?

Objective. Many studies suggest that impaired health states are valued more positively when experienced than when hypothetical. This study investigate d to what extent this discrepancy occurs and examined four possible explana tions: non-corresponding description of the hypothetical health state, new understanding due to experience with the health state, valuation shift due to a new status quo, and instability of preference. Patients and methods. F ifty-five breast cancer patients evaluated their actually experienced healt h state, a radiotherapy scenario, and a chemotherapy control scenario befor e, during, and after postoperative radiotherapy. Utilities were elicited by means of a visual analog scale (VAS), a chained time tradeoff (TTO), and a chained standard gamble (SG). Results. The discrepancy was found for all m ethods and was statistically significant for the TTO (predicted utilities: 0.89, actual utilities: 0.92, p less than or equal to 0.05). During radioth erapy, significant differences (p less than or equal to 0.01) were found be tween the utilities for the radiotherapy scenario and the actual health sta te by means of the VAS and the SG, suggesting non-corresponding description as an explanation. The utilities of the radiotherapy scenario and the chem otherapy control scenario remained stable over time, and thus new understan ding, valuation shift, and instability could be ruled out as explanations. Conclusion. Utilities obtained through hypothetical scenarios may not be va lid predictors of the value judgments of actually experienced health states . The discrepancy in this study seems to have been due to differences betwe en the situations in question (non-corresponding descriptions).