title: Evaluating the discriminatory power of EQ-5D, HUI2 and HUI3 in a US general population survey using Shannon's indices.
abstract: OBJECTIVE
  To compare quantitatively the discriminatory power of the EQ-5D, HUI2 and HUI3 in terms of absolute and relative informativity, using Shannon's indices.
  
  
  METHODS
  EQ-5D and HUI2/3 data completed by a sample of the general adult US population (N = 3,691) were used. Five dimensions allowed head-to-head comparison of informativity: Mobility/Ambulation; Anxiety/Depression/Emotion; Pain/Discomfort (EQ-5D; HUI2; HUI3); Self-Care (EQ-5D; HUI2); and Cognition (HUI2; HUI3). Shannon's index and Shannon's Evenness index were used to assess absolute and relative informativity, both by dimension and by instrument as a whole.
  
  
  RESULTS
  Absolute informativity was highest for HUI3, with the largest differences in Pain/Discomfort and Cognition. Relative informativity was highest for EQ-5D, with the largest differences in Mobility/Ambulation and Anxiety/Depression/Emotion. Absolute informativity by instrument was consistently highest for HUI3 and lowest for EQ-5D, and relative informativity was highest for EQ-5D and lowest for HUI3.
  
  
  CONCLUSIONS
  Performance in terms of absolute and relative informativity of the common dimensions of the three instruments varies over dimensions. Several dimensions are suboptimal: Pain/Discomfort (EQ-5D) seems too crude with only 3 levels, and the level descriptions of Ambulation (HUI3) and Self-Care (HUI2) could be improved. In absence of a formal measure, Shannon's indices provide useful measures for assessing discriminatory power of utility instruments.
authors.affiliation: Public Health Epidemiology, Department of Social Medicine, Academic Medical Center, 22660, 1100 DD, Amsterdam, The Netherlands. m.f.janssen@amc.uva.nl
authors.forename: Mathieu F
authors.initials: MF
authors.lastname: Bas Janssen
authors.forename: Erwin
authors.initials: E
authors.lastname: Birnie
authors.forename: Gouke J
authors.initials: GJ
authors.lastname: Bonsel
mesh_terms: D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D006233:Persons with Disabilities / Q000523:psychology; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D011594:Psychometrics / Q000295:instrumentation*; D011788:Quality of Life; D012648:Self Care; D018434:Sickness Impact Profile; D011795:Surveys and Questionnaires / Q000592:standards*; D014481:United States