Background: The EuroQol (EQ)-5D questionnaire is a generic instrument measuring health-related quality of life. Its validity, reliability, and responsiveness were assessed in a large sample of Crohn's disease (CD) and ulcerative colitis (UC) patients.
Methods: The EQ-5D was completed initially (270 CD and 232 UC subjects) and after 4 weeks (447 subjects) with a transition question rating health change. Responsiveness of EQ visual analog scale (EQ-VAS) and the United Kingdom (UK-index) and German EQ-5D index (EQ-index) scores to reported changes in health was evaluated by standardized response means (SRM) and meaningful differences (MDs).
Results: EQ-VAS and EQ-index scores correlated well with disease activity indices and differed significantly between active disease and remission groups. All scores were reliable in test-retest (ICC: EQ-VAS: 0.89; UK-index: 0.76; German EQ-index: 0.72). According to SRM, EQ-VAS was more responsive for deterioration in health than for improvement in health and was more responsive than index scores. Index scores were most responsive for deterioration in health in subjects in remission and for improved health in subjects with active disease. MDs for improved health (EQ-VAS: 10.9; UK EQ-index: 0.076; German EQ-index: 0.050) and deteriorated health (EQ-VAS: -14.4; UK EQ-index: -0.109; German EQ-index: -0.067) were significant, but MD of EQ-VAS also differed significantly according to disease activity.
Conclusions: The EQ-5D generates valid, reliable, and responsive preference-based evaluations of health in CD and UC. EQ-VAS scores were more responsive than EQ-5D index scores. Thus, small health differences that are important from the patient's perspective may not be reflected in the EQ-index.