title: Comparing the standard EQ-5D three-level system with a five-level version.
abstract: OBJECTIVE
  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).
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Public Health Epidemiology, Academic Medical Center, Amsterdam, The Netherlands. m.f.janssen@amc.uva.nl
authors.forename: Mathieu F
authors.initials: MF
authors.lastname: Janssen
authors.forename: Erwin
authors.initials: E
authors.lastname: Birnie
authors.forename: Juanita A
authors.initials: JA
authors.lastname: Haagsma
authors.forename: Gouke J
authors.initials: GJ
authors.lastname: Bonsel
mesh_terms: D000203:Activities of Daily Living; D016002:Discriminant Analysis; D005260:Female; D006305:Health Status Indicators; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D011788:Quality of Life; D015203:Reproducibility of Results