Reliability and validity of the scale for the assessment and rating of ataxia: a study in 64 ataxia patients

Abstract

The objective of this study was to test the reliability and validity of the Scale for the Assessment and Rating of Ataxia (SARA) in ataxia patients not suffering from autosomal dominant spinocerebellar ataxia (SCA). To this end, 64 patients with various ataxia disorders or stable cerebellar lesions were rated independently by two investigators. In addition to SARA, the following assessment instruments were applied: ataxia disease stage, Barthel index and part IV (functional assessment) of the Unified Huntington's Disease Rating scale (UHDRS-IV). Eighteen patients were rated twice. Inter-rater and intrarater reliability were very high with ICCs of 0.98 and 0.99. Internal consistency was high indicated by Cronbach's alpha of 0.97. Factorial analysis revealed that the rating results were mainly determined by one major factor with an eigenvalue of 6.34 which explained 52.8% of the variance. SARA score increased with disease stage (P<0.0001) and was closely correlated with Barthel index (r=-0.63, P<0.0001) and UHDRS-IV (r=-0.62, P<0.0001), but only weakly correlated with disease duration (r=0.44, P<0.001). The results suggest that SARA is a reliable and valid measure of ataxia in non-SCA ataxia patients.