Unstable Preferences: A Shift in Valuation or an Effect of the Elicitation Procedure?

Objective. Many studies suggest that impaired health states are valued more positively when experienced than when still hypothetical. We investigate to what extent discrepancies occur between hypothetical and actual value judgements and examine four possible causes for it. Patients and methods. Seventy breast cancer patients evaluated their actually experienced health state and a radiotherapy scenario before, during, and after post-operative radiotherapy. A chemotherapy scenario was evaluated as a control scenario. Utilities were elicited by means of a Visual Analog Scale (VAS), a Time Tradeoff (TTO), and a Standard Gamble (SG). Results. The utilities of the radiotherapy scenario (0.89), evaluated before radiotherapy, and the actually experienced health state (0.92), evaluated during radiotherapy, were significantly different for the TTO (p <= 0.05). For the VAS and the SG, significant differences (p <= 0.01) were found between the radiotherapy scenario and the actually experienced health state, when both were evaluated during radiotherapy. The utilities of the radiotherapy scenario and the chemotherapy scenario remained stable over time. Conclusion. Our results suggest that utilities for hypothetical scenarios remain stable over time but that utilities obtained through hypothetical scenarios may not be valid predictors of the value judgements of actually experienced health states. Discrepancies may be due to differences between the situations in question rather than to a change in evaluation of the same health state over time.