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.
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.
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).
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.