title: The factor validity of the Western Ontario Rotator Cuff Index.
abstract: BACKGROUND
  The Western Ontario Rotator Cuff Index (WORC) is a self-report questionnaire developed specifically to evaluate disability in persons with pathology of the rotator cuff of the shoulder. The authors created items in 5 categories based on a model of quality of life, but never validated this structure. The purpose of this study was to examine the validity of the original 5-domain model of the WORC by performing factor analysis.
  
  
  METHODS
  Three hundred twenty nine subjects (age, mean: 52, SD: 12) were tested prior to undergoing surgery for rotator cuff pathologies. They completed the WORC, a self-report questionnaire, which has 21 items on the effect of the rotator cuff problem on symptoms, activities and emotions. Statistical calculations included correlations between items, Cronbach's alpha of the total scale and subscales, and principal component factor analysis with oblique rotation.
  
  
  RESULTS
  Correlations ranged from .09 to .70 between all the items, from .29 to .70 between items within a subscale, and from .53 to .72 between subscale scores. Cronbach's alpha was .93 for the total scale, and .72 to .82 for the subscales. The factor analysis produced 3 factors that explained 57% of the variance. The first factor included symptoms and emotional items, the second included strength items and the third included daily activities.
  
  
  CONCLUSIONS
  The results of this study did not support the 5-domain model of the WORC.
authors.affiliation: School of Rehabilitation Science, McMaster University, Hamilton, Canada. wesselj@mcmaster.ca
authors.forename: Jean
authors.initials: J
authors.lastname: Wessel
authors.forename: Helen
authors.initials: H
authors.lastname: Razmjou
authors.forename: Yasmin
authors.initials: Y
authors.lastname: Mewa
authors.forename: Richard
authors.initials: R
authors.lastname: Holtby
mesh_terms: D000328:Adult; D004185:Disability Evaluation; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009135:Muscular Diseases / Q000503:physiopathology* / Q000523:psychology; D010146:Pain / Q000503:physiopathology; D011446:Prospective Studies; D011788:Quality of Life; D017006:Rotator Cuff; D013177:Sports; D011795:Surveys and Questionnaires / Q000592:standards*