Evaluating the reproducibility of the short version of the Western Ontario Rotator Cuff Index (Short-WORC) prospectively

BACKGROUND: Recently, a shorter version of the Western Ontario Rotator Cuff Index (Short-WORC) was created to reduce patient response burden. However, it has yet to be evaluated prospectively for reproducibility (reliability and agreement) and floor and ceiling effects. METHODS: Patients (N = 162) with rotator cuff disorders completed the Short-WORC at baseline. From this cohort, 47 patients underwent measurement of test-retest reliability within 2 to 7 days. We used the Cronbach α to determine internal consistency and the intraclass correlation coefficient (ICC(2,1)) to assess test-retest reliability. To evaluate parameters of agreement, the standard error of measurement, minimal detectable change (based on a 90% confidence interval), and Bland-Altman plots were used. RESULTS: The Cronbach α was 0.82 at baseline, and the intraclass correlation coefficient (ICC(2,1)) was 0.87. The agreement parameter was 8.4 for the standard error of measurement of agreement, and the limits of agreement fell within the range of –22.9 to 23.8. The Short-WORC is reliable over time and reflective of a patient’s true score after an intervention. CONCLUSIONS: The Short-WORC demonstrated strong reproducibility parameters and can be used for patients with rotator cuff disorders. The Short-WORC indicated no systematic bias and was reflective of the true score of both individual patients and groups of patients at 2 time points.