The factor validity of the Western Ontario Rotator Cuff Index
1 School of Rehabilitation Science, McMaster University, Hamilton, Canada
2 Department of Rehabilitation, University of Toronto, Orthopaedic and Arthritic Institute, Sunnybrook & Women's College Health Sciences Centre, Toronto, Canada
3 Student in Medical Programme, University College Cork, Cork, Ireland
4 Department of Surgery, University of Toronto, Orthopaedic and Arthritic Institute, Sunnybrook & Women's College Health Sciences Centre, Toronto, Canada
BMC Musculoskeletal Disorders 2005, 6:22 doi:10.1186/1471-2474-6-22Published: 4 May 2005
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.
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.
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.
The results of this study did not support the 5-domain model of the WORC.