Assessment of the psychometric properties of the EQ-5D-3L and EQ-5D-5L instruments in psoriasis

The aim of this study was to assess the psychometric properties of the five-level (EQ-5D-5L) in comparison with the standard three-level (EQ-5D-3L) classification systems of the EQ-5D in a sample of psoriatic patients. Psoriatic subjects ( n = 396) recruited from 16 private practicing centers from various areas of Greece self-completed the two EQ-5D versions and the Dermatology Life Quality Index, while information was also collected on socio-demographics, clinical characteristics and comorbidities. The EQ-5D-5L and EQ-5D-3L were evaluated in terms of agreement, feasibility, ceiling effects, redistribution properties, inconsistency, informativity, and convergent and known-groups validity. Missing values were negligible in both versions. The agreement between the EQ-5D-5L and the EQ-5D-3L was very high (ICC = 0.94), while the largest differences were identified for subjects with moderate health status. Ceiling effects decreased in the EQ-5D-5L system by 14.08% ( p