Willingness-to-pay utility assessment: feasibility of use in normative patient decision support systems

The authors developed an automated patient interviewing tool to elicit individuals' willingness-to-pay (WTP) utilities under conditions of uncertainty and examined the reliability of this method and its potential usefulness in clinical decision support. We tested this method in 52 healthy volunteers using a computer-based interview that trained subjects in standard gamble (SG) and WTP methods, and elicited preferences for moderate Gaucher disease using WTP and SG. We assessed the validity of the WTP method by calculating the cost-effectiveness threshold implied by subjects' WTP and SG utilities; we also assessed subjects' understanding and comfort with using WTP for decision making by a questionnaire. The WTP method had good test-retest reliability (r = 0.796), and produced a cost-effectiveness ratio and ratings for understanding and clarity that support its validity. Moreover, many subjects felt that WTP was a reasonable (83%) method for therapeutic decision making and expressed comfort (62%) in using the method for their own health care decisions. These results suggest that a probabilistic method for WTP utility assessment is potentially useful for acquiring patient preferences for use in normative decision support systems.