Cross-Cultural Adaptation, Reproducibility, and Validation of the Italian Version of the Rugby Shoulder Function Questionnaire-I

Context: Shoulder injuries are prevalent in rugby and require sport-specific outcome measures for accurate evaluation. The Rugby Shoulder Function Questionnaire (RSFQ) is designed to assess shoulder symptoms in rugby athletes, but no validated Italian version exists. This study aimed to translate, culturally adapt, and validate the Italian version of the RSFQ (RSFQ-I). Design: Cross-sectional validation study. Methods: The RSFQ was translated following standardized forward-backward procedures and administered electronically. A total of 106 Italian rugby players completed the RSFQ-I and the Italian version of the Quick Disabilities of the Arm, Shoulder, and Hand questionnaire-I at baseline; the RSFQ-I was repeated at a second timepoint. Feasibility was evaluated through completion time, missing responses, and ceiling and floor effects. Construct validity was assessed using Spearman correlation with the Quick Disabilities of the Arm, Shoulder and Hand questionnaire-I. Internal consistency was analyzed using Cronbach alpha, and test-retest reliability using the intraclass correlation coefficient (ICC2,1). Measurement error was quantified using the standard error of measurement and minimal detectable change at the 95% confidence level. Results: The RSFQ-I required approximately 5 minutes to complete, with no missing responses. Ceiling and floor effects were 0% and 15.1%, respectively. Construct validity was supported by significant correlations with the Quick Disabilities of the Arm, Shoulder and Hand questionnaire-I (P < .001). Internal consistency was high for both dominant (alpha = .92) and nondominant (alpha = .89) arms. Test-retest reliability was excellent for combined (ICC2,1 = .97), dominant (ICC2,1 = .96), and nondominant (ICC2,1 = .95) scores. The standard error of measurement was 2.77 points, and the minimal detectable change at the 95% confidence level was 7.7 points. Conclusion: The RSFQ-I demonstrates good feasibility, strong construct validity, high internal consistency, and excellent test-retest reliability. It is a valid and reliable instrument for assessing shoulder function in Italian-speaking rugby players and is suitable for use in both clinical practice and research settings.