A comparison of measurement properties between UK SF-6D and English EQ-5D-5L and Thai EQ-5D-5L value sets in general Thai population.

BACKGROUND Evidence is limited for comparative psychometric properties between EQ-5D-5L and SF-6D. Therefore, this study compared psychometric properties between those instruments using value sets from Thailand, England, and the UK in the general Thai population. METHODS A total of 1,200 participants were recruited. Agreement level was evaluated using intraclass correlation coefficients (ICCs) and Bland-Altman plots. Convergent validity with SF-12v2 was assessed by Spearman's rho correlations. Known-groups validity compared discriminant activity and sensitivity between groups. Responsiveness was assessed using standardized effect sizes (SES) and standardized response mean (SRM). RESULTS Agreement between SF-6D and Thai (ICCs = 0.51) and English (ICCs = 0.52) EQ-5D-5L index scores was good. The physical functioning demonstrated moderate to strong and moderate correlations with Thai (r = 0.50) and English (r = 0.46) EQ-5D-5L index scores, whereas SF-6D index scores strongly correlated with role emotion (r = 0.81). EQ-5D-5L was better than SF-6D at discrimination and sensitivity for gender, age, education level, household income, and number of diseases. The SF-6D was more responsive than the EQ-5D-5L for the worsened group. CONCLUSIONS Both SF-6D and EQ-5D-5L are valid among general Thai population. Further studies should reinvestigate responsiveness and determine their impacts on economic analyses among patient groups.