Comparing the Monetary Value of a Quality-Adjusted Life Year from the Payment Card and the Open-ended Format

Abstract

Background: The payment card (PC) format and the open-ended (OE) format are common methods in eliciting willing-to-pay (WTP) of one additional quality-adjusted life year (QALY). The aim of this research is to compare these two formats in eliciting the monetary value of a QALY.Methods: A contingent valuation survey was carried out using a pre-designed questionnaire with various hypothetical scenarios. The difference between the PC and the OE formats was evaluated by a two-sample equality test. Furthermore, regression analysis was carried out to control observed heterogeneity and to test theoretical validity.Results: In total, 461 individuals were involved, among whom 235 (51%) answered the PC question, while 226 (49%) answered the OE question. Excluding zero response and 1% top values, the mean WTP values of these two formats vary dramatically, which is 93,424 RMB (SD 117,601) for the PC, 143,347 RMB (SD 209,821) for the OE. Subgroup analysis indicated that the OE format tended to elicit lower values for less serious condition and higher values for more serious condition. Both formats were proved to be theoretically valid, whereas the OE technique was found to have a stronger association with most variables in the regression model than that of the PC format. Moreover, joint estimation indicated a significantly positive effect on the OE results.Conclusions: This research indicated that the PC format and OE format elicited different monetary value of a QALY, but both formats were proved to be theoretically valid. More research about the difference and the validity of various WTP eliciting methods would be recommendedfor a robust estimation of WTP/QALY.