Validity and reliability of the Turkish version of the Ottawa sitting scale in patients with multiple Sclerosis

Purpose This study aimed to examine the validity and reliability of the Turkish version of the Ottawa Sitting Scale (OSS-TR) in patients with multiple sclerosis (MS). Methods The study included 52 patients aged 29-45 who were diagnosed with MS based on McDonald criteria. To establish construct validity, structural (with confirmatory factor analysis, CFA) and convergent validity were examined. For convergent validity, the associations between the OSS-TR score with the Trunk Impairment Scale (TIS) and Berg Balance Scale (BBS) scores were analyzed. The average variance extracted (AVE) and construct reliability (CR) were calculated to enhance the assessment of convergent validity. To assess the reliability of the OSS-TR, the scale was re-administered to all participants seven days later by the same rater, and the intraclass correlation coefficient (ICC) was computed to determine the test-retest reliability. Results According to the factor analysis results, the scale was found to have a single factor. CFA indicated that the model fit indices for the OSS-TR were acceptable, verifying its construct validity. Strong correlations between the OSS-TR score and BBS (r = 0.843) and TIS (r = 0.867) scores confirmed the convergent validity of the OSS-TR (p < 0.05). Furthermore, the fact that the AVE score (0.578) was greater than 0.50 and the CR score (0.905) was greater than 0.70 supported convergent validity. The OSS-TR had high test-retest reliability (ICC = 0.953) and internal consistency (Cronbach's alpha = 0.934). Conclusion According to the results of the study, the OSS-TR is a reliable and valid tool for assessing sitting balance in Turkish-speaking MS patients.