Cross-cultural adaptation, validation, and reliability testing of the Shoulder Pain and Disability Index in the Persian population with shoulder problems.

UNLABELLED: We aimed to validate the translated and cross-culturally adapted Persian version of the Shoulder Pain and Disability Index (SPADI). The final Persian SPADI was administered to 190 patients, out of whom 83 patients returned for the retest. We administered the Persian version of the SF-36 quality-of-life inventory and the disabilities of the arm shoulder and hand (DASH) questionnaires at the first visit to assess the convergent validity. Cronbach's α was 0.94 for the total SPADI, which showed excellent internal consistency. The intraclass correlation coefficient was 0.84 for the total SPADI, which showed good reliability between the test and retest. Convergent validity was confirmed, as the Spearman correlation between total SPADI and DASH was 0.61. Moreover, there was significant correlation between the subscales of the SPADI and SF-36 scales. The Persian version of the SPADI proved to be a reliable and valid instrument to be implemented in the Persian population with shoulder disorders. LEVEL OF EVIDENCE: level II.