Valuing health states: interviews with the general public

Abstract

The objective of this study was to develop methods to elicit the general public's views on the comparative subjective value of different states of health. The resulting valuations form the basis for a set of British social preferences for use in clinical and economic evaluation of health care. The methods have proved extremely successful in generating complete data of high quality. Since the approach used is generally applicable for use in other national surveys, it is described here to encourage others to take the opportunity to generate comparable sets of social preferences. Face to face interviews, lasting approximately 1h, were conducted in the respondents’ own homes. There were 3, 395 interviews achieved (a response rate of 64%) and the sample was representative of the British general population in terms of age, sex, education, social class and geographical location. Each respondent valued 15 EuroQol health states using ranking, visual analogue scale (VAS) and time trade-off (TTO) methods, with 45 states being valued in all. Two hundred and twenty-one reinterviews were conducted after an average time of 10 weeks. Several methodological issues had to be confronted during the course of the study. These included the structure and format of the interview, the choice of health states to be valued, the determination of the sample size required, the achievement of a representative sample of the British adult population, interviewer training, data processing and data quality. Since few valuation studies have been undertaken on such a large scale, much time and effort was spent in resolving these issues. The methods used are recommended to others considering similar surveys