Does "process utility" exist? A case study of willingness to pay for laparoscopic cholecystectomy

This paper is concerned with the concept of process utility in health care. The paper begins by outlining the reasons why it might be important to include process utility in health care evaluation. Problems in defining process and outcome are then outlined, after which the discussion turns to how process utility might be detected empirically. Willingness to pay (WTP) is suggested as one means of doing so. The methods and results of a survey to test for the existence of process utility using WTP applied to laparoscopic cholecystectomy are reported. Cholecystectomy patients on a hospital waiting list were asked about their WTP for laparoscopic rather than conventional cholecystectomy. Willingness to pay was used in two ways to examine whether process is in the utility function. First, respondents were randomly allocated to receive different descriptions of laparoscopic and conventional cholecystectomy; one group receiving a description of differences between the treatments in terms of outcomes only, whilst the other group received information on differences in the process of treatment as well as on differences in outcomes. The groups were then compared in terms of their WTP. Second, regression analysis was used to test for the association between WTP and respondents' ratings of reasons for their WTP, some of these reasons reflecting process aspects and others reflecting outcome aspects. The results lead to rejection of the hypothesis that information on process of care would lead to higher WTP. However, due to the design of the study and the difficulties in defining process and outcome, it cannot be concluded that process utility does not exist. The paper concludes by suggesting alternative methods of testing for the existence of process utility.