The Western Ontario Rotator Cuff Index (WORC) is a 21 question self-report using a visual analogue scale. The patient indicates on a line how much pain, discomfort and limitation he or she experiences in various situations.
As standardized screens are always favoured in the medical community, the WORC (developed at the University of Western Ontario by Kirkley, Griffin, and Alvarez in 1998) is being embraced as an upper body compliment to the Ottawa ankle rules (see here).
Bas de Witte et al 2012 compared the WORC to 2 other shoulder questionnaires; the Diabilities of Arm, Shoulder and Hand (DASH) and the Constant Score (CS).
They had 92 patients with 3 different but common types of shoulder injury complete the questions and compared the scores. Since these questionnaires would be used to help determine the direction of treatment, standardization is important.
Internal consistency was high, a 0.95 Cronbach coefficient was found. Intraclass correlation was determined to be 0.89- this indicates high reproducibility. Correlations in score between the WORC and the CS were 0.56 and between the WORC and the DASH 0.65. As treatment progressed, correlation changed to 0.61 and 0.84 respectively. Effect size came in at 0.96 with a 0.91 response.
This tends to indicate that the WORC has high internal consistency and can be reproduced, it had good construct validity with high test-re-test reliability, and good responsiveness.
Wessel et al 2005 decided to see if the 5 domains the 21 questions are broken into add any extra data. While the overall correlation was 0.93 by Cronbach coefficient (very close to the above study) they found that by domain it varied from 0.72-0.82 and with individual questions it varied from 0.29 to 0.70. Thus while clearly the 21 questions do provide some valid data, the 5 groups they are broken into provide little in the way of reliable data.
At this time, the WORC can be used as an overall assessment for a patient’s rotator cuff pathology but should not be used to the exclusion of other tests (manual, radiological or self-reported history). In therapy, as in sport, there are no magic bullets, only different tools for different situations.