The aim of this study is a head-to-head comparison of the performance of the three-level EQ-5D (3L) and a newly developed five-level version (5L).
Eighty-two respondents valued 15 standardized disease descriptions and their own health on three response scales (3L, 5L, and visual analog scale [VAS]) for all five EQ-5D dimensions. Performance was studied in terms of feasibility, face validity, redistribution properties, ordinality, convergent validity, discriminatory power, and test–retest and interobserver reliability.
The majority of participants judged 5L as the preferred system in terms of feasibility (76%) and face validity (75%). In total, 1.1% of responses were inconsistent. Ordinality of 5L was confirmed in all cases. Convergent validity of 3L-VAS (range: 0.88–0.99) and 5L-VAS (0.90–0.99) were high and about equal. Discriminatory power (informativity) improves considerably with 5L without loss of Evenness. Interobserver reliability (0.49 vs. 0.57) and test–retest reliability (0.52 vs. 0.69) were higher in 5L.
The EQ-5D five-level version appears a valid and reliable extension of the three-level system. The new 5L system is particularly useful for describing mild health problems and monitoring population health.