Mind the gap : explanations for the differences in utilities between respondent groups

In medical decision making decisions are made by using cost-utility analyses. Utilities, in cost-utility analyses, are benefits in health estimated by comparing preferences for health states to perfect health and death. Whose__ utilities are used, those given by patients__ or by members of the general public, does matter. Previous research has shown that utilities given by patients are higher compared to those given by members of the public. The main objective of this thesis was to examine mechanisms that have been suggested to explain this gap between health state utilities. Most mechanisms suggested to influence this gap were only marginally explanatory except for focusing illusion and adaption. The public has the tendency to focus on the negative aspects of a health state. On the other hand patients adapt to their illness and take this adaptation into account. Due to focusing illusion of members of the public utilities will become lower whereas adaptation will lead to higher utilities. Whose utilities should be used in decision making depends on whose utilities are most valid. Utilities shaped by focusing illusion are biased however it is a matter of discussion if adaptation leads to invalid utilities