A comparison of the EuroQol-5D and the Health Utilities Index mark 3 in patients with rheumatic disease.

OBJECTIVE: To compare the performance of 2 commonly used utility-based health-related quality of life (HRQoL) instruments [the EuroQol-5D (EQ-5D) and Health Utilities Index mark 3 (HUI3)] in patients with rheumatic disease. METHODS: Consecutive outpatients with rheumatic diseases were interviewed twice within 2 weeks using a standard questionnaire containing the EQ-5D, HUI3, and the Medical Outcome Study Short-Form 36 Health Survey (SF-36, used to categorize health status) and assessing clinical and demographic characteristics. EQ-5D and HUI3 utility scores were compared and their construct validity and test-retest reliability were examined by comparing these scores in groups differing in health status and using intraclass correlation coefficients (ICC), respectively. RESULTS: EQ-5D and HUI3 utility scores in 114 patients differentiated well between varying health states; e.g., patients with higher SF-36 vitality scores had better EQ-5D and HUI3 utility scores (mean: 0.79 for both instruments) than patients with lower vitality scores (mean: 0.68 and 0.69, respectively) (p < 0.01 for both comparisons). ICC values for the EQ-5D and HUI3 were 0.64 and 0.75, respectively (n = 90, median interval: 7 days). EQ-5D and HUI3 utility scores were similar (mean +/- SD: 0.75 +/- 0.21 vs 0.76 +/- 0.17, p = 0.647, paired t test) and showed moderate correlation (Spearman's r: 0.45, p < 0.001). Differences were present in patients' responses to these 2 instruments: e.g., 12 patients reporting no problems with mobility (EQ-5D item) reported different levels of disability with ambulation (HUI3 item). CONCLUSIONS: The EQ-5D and HUI3 performed equally well in measuring utility-based HRQoL in patients with rheumatic disease, although they measured slightly different, though related, dimensions of health.

Do English and Chinese EQ-5D versions demonstrate measurement equivalence? An exploratory study.

BACKGROUND: Although multiple language versions of health-related quality of life instruments are often used interchangeably in clinical research, the measurement equivalence of these versions (especially using alphabet vs pictogram-based languages) has rarely been assessed. We therefore investigated the measurement equivalence of English and Chinese versions of the EQ-5D, a widely used utility-based outcome instrument. METHODS: In a cross-sectional study, either EQ-5D version was administered to consecutive outpatients with rheumatic diseases. Measurement equivalence of EQ-5D item responses and utility and visual analog scale (EQ-VAS) scores between these versions was assessed using multiple regression models (with and without adjusting for potential confounding variables), by comparing the 95% confidence interval (95%CI) of score differences between these versions with pre-defined equivalence margins. An equivalence margin defined a magnitude of score differences (10% and 5% of entire score ranges for item responses and utility/EQ-VAS scores, respectively) which was felt to be clinically unimportant. RESULTS: Sixty-six subjects completed the English and 48 subjects the Chinese EQ-5D. The 95%CI of the score differences between these versions overlapped with but did not fall completely within pre-defined equivalence margins for 4 EQ-5D items, utility and EQ-VAS scores. For example, the 95%CI of the adjusted score difference between these EQ-5D versions was -0.14 to +0.03 points for utility scores and -11.6 to +3.3 points for EQ-VAS scores (equivalence margins of -0.05 to +0.05 and -5.0 to +5.0 respectively). CONCLUSION: These data provide promising evidence for the measurement equivalence of English and Chinese EQ-5D versions.