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.