Economic evaluations alongside randomised controlled trials (RCTs) are increasingly being designed to prospectively collect patient-specific resource use and preference-based health status (utility) data. This paper examines the ways in which preference-based health status (utility) data are used to generate quality adjusted life years (QALYs). A literature review was carried out which identified 23 published cost utility analyses suitable for inclusion. The methodology employed to calculate QALYs was not always consistent, as well as being poorly reported. The use of different methodologies in the calculation of QALYs may influence the magnitude and direction of results of evaluations. Analysts need to be consistent and fully transparent in the methodology chosen to calculate QALYs.
2004 John Wiley & Sons, Ltd.