Cross-cultural adaptation and measurement properties of an italian version of the Western Ontario Shoulder Instability Index (WOSI).

STUDY DESIGN: Clinical measurement study. OBJECTIVES: To translate and cross-culturally adapt the Western Ontario Shoulder Instability Index (WOSI) into Italian, and to evaluate its measurement properties in patients with shoulder instability secondary to a first traumatic anterior dislocation. BACKGROUND: The WOSI was developed for English-speaking patients. To date, no Italian version of the WOSI exists. METHODS: The WOSI was cross-culturally adapted to Italian according to established guidelines. Sixty-four (16 women, 48 men) patients with unilateral shoulder anterior instability were prospectively recruited for the purposes of this study. Internal consistency, test-retest reliability, construct validity, and responsiveness of the WOSI were evaluated. RESULTS: The Italian version of the WOSI showed a high degree of internal consistency, with a Cronbach's alpha of 0.93 (95% CI, 0.91 to 0.96). The test-retest reliability was high for both short-term (3 days, 64 patients) and medium-term (14 weeks, 20 patients) test-retest, with intraclass correlation coefficients of 0.95 (95% CI, 0.90 to 0.97) and 0.92 (95% CI, 0.89 to 0.95), respectively. The WOSI was more closely correlated to the DASH than the SF-36 (r = 0.794 and 0.113, respectively). The receiver-operating characteristic curve analysis revealed that the WOSI was more responsive than the DASH (P = 0.03), with an area under the curve of 0.90 (95% CI, 0.78 to 0.97) for the WOSI and 0.76 (95% CI, 0.61 to 0.88) for the DASH. CONCLUSION: The Italian version of the WOSI is a valid, reliable, and responsive tool that can be used to measure function in Italian speaking patients with shoulder instability due to a first traumatic anterior dislocation