title: Performance of the EQ-5D in patients with irritable bowel syndrome.
abstract: OBJECTIVE
  The EQ-5D is a standardized, nondisease-specific instrument for evaluating patients' preference-based valuations of health-related quality of life (HRQoL). This study's purpose was to determine the psychometric properties of EQ-5D in patients with irritable bowel syndrome (IBS).
  
  
  METHODS
  Data from four European IBS studies were assessed: UK (n = 161 and n = 297), Spain (n = 503), and Germany (n = 100). The EQ-5D is a five-item health state descriptive system used to develop health states (EQ-5D(INDEX)) and a visual analog scale (VAS) (0-100 from worst to best imaginable health state, EQ-5D(VAS)). Measures used with the EQ-5D included the SF-36, Irritable Bowel Syndrome--Quality of Life (IBS-QOL), and both subjective and clinical global assessments of IBS. Convergent validity was assessed using SF-36 and IBS-QOL data, discriminant validity using global ratings of IBS severity, and responsiveness by subjective and physician assessment of condition.
  
  
  RESULTS
  Moderate-to-high associations (r >or= 0.33) were seen between the EQ-5D(VAS) and the SF-36 and IBS-QOL subscales. Mean response scores to EQ-5D(INDEX) dimensions and the EQ-5D(VAS) score were significantly better for control patients than for patients with IBS (all P < 0.01). The EQ-5D(VAS) was able to discriminate between levels of pain severity (quartiles, P < 0.001; mild/moderate/severe, P < 0.05) and general health severity (mild/moderate/severe, P < 0.001). The EQ-5D(VAS) and the EQ-5D(INDEX) were responsive in patients using both a self-perceived (Subject's Global Assessment) and physician-rated (Clinic Global Assessment) improvement.
  
  
  CONCLUSIONS
  The EQ-5D performs well in comparison to general and disease-specific outcomes. It is a valid and responsive measure that can be used to generate preference-based valuations of HRQoL in patients with IBS and useful for comparisons in clinical and cost-effectiveness studies.
authors.affiliation: Health Research Associates, Inc., Mountlake Terrace, WA 98043, USA. bushnell@hrainc.net
authors.forename: Donald M
authors.initials: DM
authors.lastname: Bushnell
authors.forename: Mona L
authors.initials: ML
authors.lastname: Martin
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Ricci
authors.forename: Andrea
authors.initials: A
authors.lastname: Bracco
mesh_terms: D000328:Adult; D003362:Cost-Benefit Analysis; D005260:Female; D005858:Germany; D006304:Health Status; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000503:physiopathology* / Q000523:psychology / Q000534:rehabilitation; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D017060:Patient Satisfaction / Q000191:economics / Q000706:statistics & numerical data*; D011594:Psychometrics / Q000295:instrumentation*; D011788:Quality of Life; D015203:Reproducibility of Results; D018434:Sickness Impact Profile; D013030:Spain; D011795:Surveys and Questionnaires; D006113:United Kingdom