Estimating a constant WTP for a QALY—a mission impossible?

Economic evaluations are an important input to decision-making and priority-setting in the health care sector. Measuring preferences for health improvements, as the demand-side value (willingness to pay) of gaining a quality-adjusted life year (QALY), is one relevant component in the interpretation of the results from health economic evaluations. Our article addresses whether willingness to pay for a QALY (WTP-Q) is sensitive to the size of the health differences and the probability for improvement. We use data from a contingent valuation survey based on 1400 respondents conducted in the spring of 2014. The results show that the expectation of sensitivity to scope, or higher WTP to the larger expected quality of life improvement, is not supported. We find WTP-Q values that conform reasonably well to previous studies in Sweden.