title: Test-retest reliability of an interactive voice response version of the EQ-5D in a sample of cancer survivors.
abstract: BACKGROUND
  Electronic data capture technologies, such as interactive voice response (IVR) systems, are emerging as important alternatives for collecting patient-reported outcome data.
  
  
  OBJECTIVE
  The objective of this study was to assess the test-retest reliability of an IVR version of the EQ-5D.
  
  
  METHODS
  Outpatient cancer clinic patients (n = 127) were asked to complete the IVR-based EQ-5D twice, 2 days apart. The analyses tested for mean differences (paired t-test) and test-retest reliability (intraclass correlation coefficient [ICC]) to assess measurement stability over time. Equivalence of the means was established if the 95% confidence interval (CI) was within the minimally important difference (MID) interval; namely -0.035 to 0.035 for the EQ-5D index and -3.0 to 3.0 for the visual analog scale (i.e. EQ VAS). Adequacy of the ICC was established by testing whether it differed from a value of 0.70.
  
  
  RESULTS
  Both administrations were completed per protocol by 114 subjects (EQ-5D index) and 110 subjects (EQ VAS). For the EQ-5D index, the means (SD) of the first and second administrations were 0.871 (0.14) and 0.871 (0.15), respectively. The 95% CI of the mean difference was -0.013, 0.013, within the equivalence interval. The ICC was 0.876 (95% lower bound of 0.826) and was significantly different from 0.70. The EQ VAS means (SD) were 81.3 (17.5) and 80.8 (17.5), respectively. The 95% CI of the mean difference was -0.598, 1.617, within the equivalence interval. The EQ VAS ICC was 0.944 (95% lower bound of 0.919) and was significantly greater than 0.70.
  
  
  CONCLUSIONS
  This analysis provides substantial evidence that the scores obtained from the IVR version of the EQ-5D are reliable upon repeated administrations.
authors.affiliation: Patient-Reported Outcome Consortium, Critical Path Institute, Tucson, AZ, USA. jlundy@c-path.org
authors.forename: J Jason
authors.initials: JJ
authors.lastname: Lundy
authors.forename: Stephen Joel
authors.initials: SJ
authors.lastname: Coons
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000523:psychology*; D017063:Outcome Assessment, Health Care / Q000379:methods; D011594:Psychometrics; D011788:Quality of Life; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D017741:Survivors / Q000523:psychology*; D013689:Telephone