Purpose: The EuroQol five-dimension questionnaire (EQ-5D) is the most commonly used instrument to obtain utility values for cost-effectiveness analyses of treatments for Crohn's disease (CD). We aimed to compare the measurement properties of the two adult versions of EQ-5D (EQ-5D-3L and EQ-5D-5L) in patients with CD.
Methods: Between 2016 and 2017, a multicentre cross-sectional survey was carried out. Consecutive outpatients with CD completed the 3L, 5L and EQ visual analogue scale (VAS). Disease severity was graded by the Crohn's Disease Activity Index (CDAI) and Perianal Disease Activity Index (PDAI). The 3L and 5L were compared in terms of feasibility, agreement, ceiling effect, redistribution properties, discriminatory power, convergent and known-groups validity.
Results: Two-hundred and six patients (54.9% male, mean age 35 ± 11 years) participated in the survey. For 3L, 25 unique health states were observed versus 59 for the 5L. The overall ceiling effect decreased from 29.6% (3L) to 25.5% (5L). Absolute discriminatory power improved (mean Shannon index 0.84 vs. 1.18). The 3L correlated stronger with EQ VAS and CDAI scores, whereas the 5L with PDAI. The 5L demonstrated a better known-groups validity on the basis of age, perianal fistulas, extraintestinal manifestations and disability.
Conclusions: This is the first study to report the impact of CD on quality of life using the EQ-5D-5L questionnaire. The 5L seems to perform better than 3L in terms of feasibility, ceiling effect, discriminatory power and known-groups validity. Understanding the differences in psychometrics between the 3L and 5L is essential as they have substantial implications for financial decision-making about CD treatments.
Keywords: Crohn’s disease; EQ-5D; Health-related quality of life; Psychometrics.