Cross cultural adaptation and validation of the Greek version of the Western Ontario Rotator Cuff (WORC) index

Abstract

Purpose We aimed to translate and cross-culturally adapt the Western Ontario Rotator Cuff index into Greek (WORC-GR) and evaluate its reliability and validity in a Greek speaking population with rotator cuff (RC) disorders. Materials and methods Translation and cross-cultural adaptation process followed published guidelines. Content and face validity were assessed by 9 experts and 16 patients with RC pathologies, respectively. Internal structure, reliability, measurement error, and convergent validity (correlation with the Disability of the Arm, Shoulder and Hand – DASH, Shoulder Pain and Disability Index – SPADI, and Short Form-36) of the index were evaluated in 104 participants (44.2% women, mean age ± SD: 44.9 ± 15.01 years) with RC related pain. Results The WORC-GR showed excellent item and scale content validity index (0.875–1.00 and 0.975, respectively), internal consistency (Cronbach’s alpha range 0.749 − 0.903) and test-retest reliability (intraclass correlation coefficient: 0.942, 95% CI: 0.913–0.961). Factorial validity testing revealed a 4-factor structure explaining 69.7% of the total variance. High positive correlations were found with DASH (r = 0.806) and SPADI (r = 0.852). Conclusions WORC-GR is a reliable and valid instrument to assess symptoms in patients with RC disorders. Further research on the content validity, internal structure, and responsiveness of the tool is required. Implications for rehabilitation The Greek version of WORC (WORC-GR) is a clear and comprehensible patient reported outcome measure. WORC-GR has excellent internal consistency, test-retest reliability and with no floor and ceiling effects. WORC-GR is a valid outcome measure for patients with rotator cuff disorders.