title: Reproducibility: Reliability and agreement of short version of Western Ontario Rotator Cuff Index (Short-WORC) in patients with rotator cuff disorders.
abstract: BACKGROUND
  Recently, a shorter version of Western Ontario Rotator Cuff Index (Short-WORC) was proposed as a subset of 7 items from the original 21-item WORC. However, the reproducibility of the Short-WORC has not been established.
  
  
  OBJECTIVE
  To determine reproducibility (reliability and agreement) of the Short-WORC among patients with rotator cuff disorders (RCDs).
  
  
  METHODS
  Patients (n = 153) diagnosed with RCD completed the WORC at baseline and at 3 months post-operatively (n = 146). The Short-WORC was extracted from the full version of WORC. From this retrospective cohort, 43 patients were retested within 5 weeks, if they remained stable. Cronbach's alpha (α) and intra class correlation coefficients (ICC2,1) were used to assess internal consistency and test-retest reliability respectively. Standard error measurement (SEM), minimal detectable change (MDC90) and Bland Altman (BA) plots were used to assess agreement.
  
  
  RESULTS
  No floor and ceiling effects were reported for either the Short-WORC or WORC. Cronbach's α were 0.84 and 0.90 at baseline and 0.89 and 0.95 at 3 month of follow up for Short-WORC and WORC respectively. The ICC2,1 were 0.89 and 0.91 for the Short-WORC and WORC respectively. The agreement parameters for the Short-WORC were: SEMagreement = 8.8, MDC90individual = 20.3, MDC90group = 5.1. We found substantial agreement between the two versions of WORC on BA plots with minimal (mean difference (d) <1) systematic differences between them. The limits of agreement (LOA) between two versions of WORC were similar across sessions and fell within range of -11.7 to 13.2 points at test and -14.7 to 14.7 points at retest.
  
  
  CONCLUSIONS
  Short-WORC and WORC demonstrates strong reproducibility and can be used for group and individual comparison of health-related quality of life (HRQoL) among patients with RCD. Wider LOA may be expected when using the Short-WORC for individual patient assessment. Reproducibility data is essential, but should be supplemented by validation of actual Short-WORC with samples representing the spectrum of RCD.
  
  
  METHODS
  N/A.
authors: School of Rehabilitation Sciences, McMaster University, Canada. Electronic address: dewann@mcmaster.ca.
authors: Neha
authors: N
authors: Dewan
authors: School of Rehabilitation Sciences, McMaster University, Canada; Hand and Upper Limb Center, St. Joseph's Hospital, London, ON, Canada; Department of Physical Therapy, University of Western Ontario, Canada; Department of Surgery, University of Western Ontario, Canada.
authors: Joy C
authors: JC
authors: MacDermid
authors: School of Rehabilitation Sciences, McMaster University, Canada; Queen's University, Kingston, ON, Canada.
authors: Norma
authors: N
authors: MacIntyre
authors: Hand and Upper Limb Center, St. Joseph's Hospital, London, ON, Canada; Department of Surgery, University of Western Ontario, Canada.
authors: Ruby
authors: R
authors: Grewal
mesh_terms: D000328:Adult; D000368:Aged; D016208:Databases, Factual; D004185:Disability Evaluation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009864:Ontario; D019637:Orthopedic Procedures / Q000379:methods; D010147:Pain Measurement; D011788:Quality of Life; D016059:Range of Motion, Articular / Q000502:physiology*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D018570:Risk Assessment; D017006:Rotator Cuff / Q000503:physiopathology / Q000601:surgery; D012720:Severity of Illness Index; D019534:Shoulder Impingement Syndrome / Q000175:diagnosis* / Q000601:surgery; D020069:Shoulder Pain / Q000175:diagnosis* / Q000601:surgery; D016896:Treatment Outcome
keywords: Minimal detectable change; Quality of life; Reliability; Rotator cuff tear; Shoulder pain; Western Ontario Rotator Cuff Index