Cross-cultural adaptation and validation of the Korean version of the EQ-5D in patients with rheumatic diseases

Objectives: This study aimed to determine the cross-cultural adaptation and validation of the Korean version of the EQ-5D in rheumatic conditions. Methods: Translation, back-translation and cognitive debriefing were performed according to the EuroQol group's guidelines. For validity, 508 patients were recruited and administered the EQ-5D, Short-Form 36 and condition-specific measures. Construct validity and sensitivity were evaluated by testing a-priori hypotheses. For reliability, another 57 patients repeated the EQ-5D at 1-week interval, and intra-class correlations (ICC) and kappa statistics were estimated. For responsiveness, another 60 patients repeated it at 12-week interval within the context of clinical trial, and standardized response mean(SRM) were calculated. Results: The cross-cultural adaptation produced no major modifications in the scale. The associations of the EQ-5D with the generic- and condition-specific measures were observed as expected in hypotheses the higher: EQ-5D(index) and EQ-5D(VAS) scores, the better health status by generic- or condition-specific measures, and the better functional class. The ICCs were 0.751 and 0.767, respectively, and kappa ranged from 0.455 to 0.772. The SRM were 0.649 and 0.410, respectively. Conclusion: The Korean EQ-5D exhibits good validity and sensitivity in various rheumatic conditions. Although its reliability and responsiveness were not excellent, it seems acceptable if condition-specific measures are applied together.