Abstract
The Ottawa Sitting Scale is a tool for the multidimensional assessment of sitting balance. This study aimed to investigate the validity, reliability, and psychometric properties of the Turkish version of the Ottawa Sitting Scale (OSS-TR) in Turkish-speaking patients with Parkinson's disease (PD). The study included 56 patients diagnosed with PD based on the UK Brain Bank Criteria. Construct validity of the OSS-TR was established through the evaluation of structural and convergent validity. Explanatory factor analysis and confirmatory factor analysis (CFA) were carried out to determine the structural validity. Convergent validity was analysed by examining the relationships between OSS-TR with the Berg Balance Scale (BBS) and Trunk Impairment Scale (TIS). The test-retest reliability of the scale was assessed by intraclass correlation coefficient (ICC) and internal consistency was assessed by Cronbach's alpha coefficient. The good fit determined according to the model fit criteria based on the CFA results confirmed the structural validity. Furthermore, the high associations between OSS-TR with the BBS (r = 0.766) and TIS (r = 0.720) supported convergent validity (p < 0.05). Test-retest reliability of the OSS-TR was excellent (ICC = 0.867). Moreover, internal consistency was high (Cronbach's alpha = 0.948). The OSS-TR is a valid and reliable instrument for assessing sitting balance in Turkish-speaking PD patients. Regarding the results of the study, OSS-TR can be considered useful in the evaluation of sitting balance among PD patients in clinical and research settings.