Quality of Life Measurement of Patients Receiving Treatments for Gallstone Disease: Options, Issues and Results

The paper discusses the methods for determining health state values in the context of a study of treatment options for gallstone disease.* The study design is a cost utility analysis (CUA) and the technique used to measure quality of life had to meet the specific requirements of a CUA, viz that the units of measurement were appropriate for the calculation of quality adjusted life years. The paper examines the selection of a measurement technique and the related issue of how the measurement task was controlled to ensure the eliciting of valid responses. It also discusses the psychometric properties of the two measurement techniques used, namely the time-trade off technique (TTO) and the rating scale (RS). It supports the findings of other studies that the psychological quantity measured by the two scaling techniques is either quite different or measured in different units. Consequently, the magnitude of the measured change in QALYs would depend upon the choice of a scaling technique. It argues for the adoption of a de facto gold standard for measuring health state values for CUA via a generic multi attribute utility index. * In two companion papers Street (1993) presents the methods and results from the analysis of treatment costs, and Cook and Richardson (1993) discuss the method adopted in the construction of health state scenarios used for the quantification of treatment outcomes. An overview of the study, its methods, results and the sensitivity of these to various assumed values is presented in Cook, Richardson and Street (1993).