Cross-cultural adaptation, validation and responsiveness of the Persian version of Western Ontario shoulder instability index questionnaire in Persian patients with shoulder instability.

INTRODUCTION:To translate, cross-culturally adapt, and psychometric testing the Western Ontario Shoulder Instability index (WOSI) into Persian. METHODS:Seventy-two patients diagnosed with shoulder instability participated in reliability, construct validity, and responsiveness analysis. All the patients filled out the WOSI with an interval of two weeks to assess reliability. The shortened Disability of Arm, Shoulder and Hand (Quick-DASH), Shoulder Pain and Disability Index (SPADI), and the 36-Item Short-Form Survey (SF-36) were assessed to evaluate construct validity. In order to assess responsiveness patients filled out WOSI before and after the physiotherapy and global rating of change scale at last session of physiotherapy. Reliability was assessed by intra-class correlation coefficient (ICC (1,2)), construct validity by two tailed Pearson (r), and responsiveness by longitudinal validity and receiver operating characteristics (ROC) curve analysis. RESULTS:The ICC (1,2) was 0.90 and correlation analysis revealed high level of correlation with: Quick-DASH (r = 0.82); SPADI (r = 0.72); physical SF-36 (r = -0.52); and mental SF-36 (r = -0.48). Responsiveness analysis demonstrated the area under curve was 0.90, with minimal clinical important difference 46.87. CONCLUSION:We found the Persian-WOSI as a valid, reliable, and responsive questionnaire to evaluate quality of life of patients with shoulder instability.