Validity and reliability of the EQ-5D for cancer patients in Korea

The purpose of this study was to assess the validity and reliability of the Korean version of the EQ-5D health questionnaire for use in patients with cancer in Korea. Patients with colorectal cancer were recruited from one ambulatory cancer center. Each participant consecutively self-administered the EQ-5D, the EORTC QLQ-C30, and the Short Form-36 (SF-36). Discriminatory ability was evaluated by comparing the SF-36 subscales with their corresponding EQ-5D dimensions. Convergent validity was assessed by examining the correlations between the EQ-5D index, EORTC QLQ-C30 subscales, and SF-36 scale and summary scores. Test-retest reliability was also evaluated. Subjects reporting problems in each EQ-5D dimension showed lower scores on all SF-36 subscales. As expected, the relationships were stronger between the EQ-5D functional dimensions and physical function on the EORTC QLQ-C30 and between the EQ-5D anxiety/depression dimension and emotional function on the EORTC QLQ-C30. The EQ-5D index and SF-36 scales were moderately or highly correlated. intraclass correlation coefficient of the EQ-5D index was 0.45. The Korean version of the EQ-5D may be a valid tool for assessing the health-related quality of life of patients with cancer. However, further research is needed to determine the reliability of the Korean EQ-5D over different time intervals and disease conditions.