What is the value of social values? The uselessness of assessing health-related quality of life through preference measures

Responses to the EQ5-D of a sample of 10,972 patients from 10 countries enrolled in an observational study of the treatment of schizophrenia in Europe were used for this purpose. Two different methods of scoring the EQ-5D where compared: 'weighting the items' of the questionnaire through the UK official weight coefficients, and 'non-weighting the items'. Pearson's, Spearman's, and two-way mixed parametric intraclass correlation coefficients were used to estimate the association of the scores obtained in both ways.The association between weighted and unweighted Euroqol scores was extremely high (Pearson's r = 0.91), as was the association between their ranks (Spearman's ρ = 0.93). The intraclass correlation coefficient obtained (0.89) also suggested that the concordance between the score distributions was prominent.A non-weighted approach to score the EQ5-D is enough to explain a high proportion of variance in scores obtained through the use of utilities. The differential contribution of weights based on population preference values is therefore minimal and, in our opinion, negligible.The use of preference-based measures in the evaluation of health outcomes has extended considerably over the last decade [1-4]. Their advantage over other types of general instruments in the evaluation of health related quality of life (HRQOL), such as the SF-36 [5], the Sickness Impact Profile [6], and the Nottingham Health Profile [7], supposedly lies in the fact that preference measures result in a single numerical index that reflects the value of social preferences through health states [8]. These numerical indices are finally used to calculate the Quality Adjusted Life Years (QALYs) [9] required to effect cost-utility studies [10] (cost-utility analysis is a form of economic evaluation that focuses particular attention on the quality of the health outcomes produced by health programmes or treatments) [11].Broadly speaking, the preference-based approach assumes that the social value