Willingness to pay for a QALY: past, present and future.

This paper is focused on establishing why a willingness-to-pay per quality-adjusted life-year value is needed and how such a value can be used in healthcare decision-making. Studies that have estimated willingness-to-pay per quality-adjusted life-year values from stated preference data are reviewed and categorized into three groups. These studies are then compared within and between groups highlighting the limitations of existing studies and their suitability for use in policy-making. The future of such work will be discussed, noting key issues for consideration and debate.