title: A Test-Retest Reliability Study of the Whiplash Disability Questionnaire in Patients With Acute Whiplash-Associated Disorders.
abstract: OBJECTIVE
  The purpose of this study was to determine the test-retest reliability and the Minimal Detectable Change (MDC) of the Whiplash Disability Questionnaire (WDQ) in individuals with acute whiplash-associated disorders (WADs).
  
  
  METHODS
  We performed a test-retest reliability study. We included insurance claimants from Ontario who were at least 18 years of age, within 21 days of their motor vehicle collision and diagnosed as having acute WAD grades I to III. The WDQ, a 13-item questionnaire scored from 0 (no disability) to 130 (complete disability), was administered to all participants at baseline and by telephone 3 days later. We computed the intraclass correlation coefficient (model 2,1) and the MDC with 95% confidence intervals (CIs; MDC95).
  
  
  RESULTS
  The mean (SD) age of the 66 participants was 41.6 (12.7) years and 71.2% were female. Twenty-nine percent had WAD I and 71.2% had WAD II. Time since injury ranged from 0 to 19 days. The mean (SD) baseline WDQ score was 49.3 (28.8) and 46.5 (29.8) 3 days later. The intraclass correlation coefficient for the WDQ total score was 0.89 (95% CI, 0.85-0.92) in the entire sample and 0.83 (95% CI, 0.69-0.93) for the 15 participants reporting no change in neck pain. The MDC95 of the WDQ was 21.4 (SD = 14.9) for participants reporting no change.
  
  
  CONCLUSIONS
  The WDQ was reliable in individuals with acute WAD. There is 95% confidence that a change of approximately one-sixth of the total score is beyond the daily variation of a stable condition. This level of measurement error must be taken into consideration when interpreting change in WDQ scores.
authors.affiliation: Postdoctoral Fellow, Faculty of Health Sciences, University of Ontario Institute of Technology, Toronto, Canada; Adjunct Professor, Graduate Education and Research Programs, Canadian Memorial Chiropractic College, Toronto, Canada. Electronic address: maja.stupar@mail.utoronto.ca.
authors.forename: Maja
authors.initials: M
authors.lastname: Stupar
authors.affiliation: Associate Professor and Canada Research Chair, Faculty of Health Sciences, University of Ontario Institute of Technology, Toronto, Canada; Director, UOIT-CMCC Centre for the Study of Disability Prevention and Rehabilitation, Toronto, Canada; Associate Professor, Division of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, Canada.
authors.forename: Pierre
authors.initials: P
authors.lastname: Côté
authors.affiliation: Associate Professor, Department of Occupational Science and Occupational Therapy, University of Toronto, Toronto, Canada; Director and Scientist, Musculoskeletal Health and Outcomes Research, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada; Senior Scientist, Institute for Work & Health, Toronto, ON, Canada.
authors.forename: Dorcas E
authors.initials: DE
authors.lastname: Beaton
authors.affiliation: Associate Professor, Department of Sports Science and Clinical Biomechanics, Faculty of Health, University of Southern Denmark, Odense, Denmark; Assistant Professor, Division of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, Canada.
authors.forename: Eleanor
authors.initials: E
authors.lastname: Boyle
authors.affiliation: Senior Scientist, Division of Health Care and Outcomes Research, Toronto Western Research Institute, University Health Network, Toronto, Canada; Professor, Division of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, Canada.
authors.forename: J David
authors.initials: JD
authors.lastname: Cassidy
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D014911:Whiplash Injuries / Q000150:complications* / Q000175:diagnosis*; D055815:Young Adult
keywords: Patient Outcome Assessment; Reproducibility of Results; Whiplash Injuries