A shortened version of the Western ontario rotator cuff disability index: development and measurement properties.

PURPOSE: The objective of this study was to develop and examine the measurement properties of a shortened version of the Western Ontario Rotator Cuff Index (WORC), the SHORTWORC, in individuals with rotator-cuff pathology.
METHODS: The study occurred in two stages, both using secondary analysis of existing data sets. The first stage used cross-sectional data from candidates for rotator-cuff surgery to develop the SHORTWORC. The second stage examined various measurement properties of the SHORTWORC by analyzing scores from the WORC, the American Shoulder and Elbow Surgeons questionnaire, and the Constant-Murley score obtained from patients before and after rotator-cuff surgery. Approaches to validating the SHORTWORC included calculating the standard error of measurement (SEM) at an instant in time, performing a confirmatory factor analysis, correlating findings among the questionnaires, and examining differences between men and women. Sensitivity to change was investigated using standardized response mean and relative efficiency.
RESULTS: Data for 712 patients were used to develop the SHORTWORC, the final version of which consisted of 7 questions. Data for 166 patients (86 men, 80 women; mean age 57±11 years) were used for validation. The SEM based on internal consistency (SEMIC) was calculated as 7.43 SHORTWORC points. The SHORTWORC had similar convergent validity (r=0.72-0.82) and sensitivity to change (SRM=1.20 vs. 1.25, p>0.05) to the longer version. The relative efficiency of the SHORTWORC was 3.19 times that of the WORC (95% CI, 1.50-71.51) in discriminating men's from women's level of disability.
CONCLUSIONS: The SHORTWORC has indicators of validity, relative efficiency, and sensitivity to change comparable to those of the original version but has a smaller response burden. Purpose: The objective of this study was to develop and examine the measurement properties of a shortened version of the Western Ontario Rotator Cuff Index (WORC), the SHORTWORC, in individuals with rotator-cuff pathology.
Methods: The study occurred in two stages, both using secondary analysis of existing data sets. The first stage used cross-sectional data from candidates for rotator-cuff surgery to develop the SHORTWORC. The second stage examined various measurement properties of the SHORTWORC by analyzing scores from the WORC, the American Shoulder and Elbow Surgeons questionnaire, and the Constant–Murley score obtained from patients before and after rotator-cuff surgery. Approaches to validating the SHORTWORC included calculating the standard error of measurement (SEM) at an instant in time, performing a confirmatory factor analysis, correlating findings among the questionnaires, and examining differences between men and women. Sensitivity to change was investigated using standardized response mean and relative efficiency.
Results: Data for 712 patients were used to develop the SHORTWORC, the final version of which consisted of 7 questions. Data for 166 patients (86 men, 80 women; mean age 57±11 years) were used for validation. The SEM based on internal consistency (SEMIC) was calculated as 7.43 SHORTWORC points. The SHORTWORC had similar convergent validity (r=0.72−0.82) and sensitivity to change (SRM=1.20 vs. 1.25, p>0.05) to the longer version. The relative efficiency of the SHORTWORC was 3.19 times that of the WORC (95% CI, 1.50–71.51) in discriminating men's from women's level of disability. Conclusions: The SHORTWORC has indicators of validity, relative efficiency, and sensitivity to change comparable to those of the original version but has a smaller response burden.