Abstract
BACKGROUND: No questionnaire is currently available for use in patients with shoulder pain in an Indonesian-speaking population. This study aimed to translate the Oxford Shoulder Score (OSS) into Indonesian and assess its validity and reliability for use in Indonesian-speaking patients with shoulder pain. METHODS: After a forward and backward translation procedure, the validity and reliability of the questionnaire were investigated. All patients who were treated in a hospital in Indonesia for shoulder pain during the inclusion period were asked to complete 3 questionnaires: the Indonesia-OSS (I-OSS), the Medical Outcomes Study 12-Item Short-Form Health Survey, and the American Shoulder and Elbow Surgeons questionnaire. Participants were asked to complete the I-OSS a second time after a 1-week interval. Following Consensus-Based Standards for the Selection of Health Measurement Instruments guidelines, construct validity, test-retest reliability, internal consistency, floor and ceiling effects, and measurement error were determined. The Bland-Altman method was used to explore systematic bias. RESULTS: Data of 100 patients could be used to determine validity, and data of 87 patients to determine test-retest reliability. Construct validity can be considered good, as more than 75% of the predefined hypotheses on correlations between the I-OSS and the other questionnaires could be confirmed. An intraclass correlation coefficient value of 0.99 was found, indicating good test-retest reliability. A Cronbach's α of 0.95 implied good internal consistency, and no floor or ceiling effects were found. The standard error of measurement was 1.8, with minimal detectable change at the individual level was 5.1, and at the group level was 0.5. Bland-Altman analysis showed no systematic bias. CONCLUSION: The I-OSS can be considered a valid and reliable questionnaire for Indonesian-speaking patients with shoulder pain.