Scale for the assessment and rating of ataxia -: Development of a new clinical scale

Objective: To develop a reliable and valid clinical scale measuring the severity of ataxia. Methods: The authors devised the Scale for the Assessment and Rating of Ataxia ( SARA) and tested it in two trials of 167 and 119 patients with spinocerebellar ataxia. Results: The mean time to administer SARA in patients was 14.2 +/- 7.5 minutes ( range 5 to 40). Interrater reliability was high, with an intraclass coefficient ( ICC) of 0.98. Test-retest reliability was high with an ICC of 0.90. Internal consistency was high as indicated by Cronbach's alpha of 0.94. Factorial analysis revealed that the rating results were determined by a single factor. SARA ratings showed a linear relation to global assessments using a visual analogue scale, suggesting linearity of the scale ( p < 0.0001, r(2) = 0.98). SARA score increased with the disease stage ( p < 0.001) and was closely correlated with the Barthel Index ( r = - 0.80, p < 0.001) and part IV ( functional assessment) of the Unified Huntington's Disease Rating Scale ( UHDRS-IV) ( r = - 0.89, p < 0.0001), whereas it had only a weak correlation with disease duration ( r = 0.34, p < 0.0002) Conclusions: The Scale for the Assessment and Rating of Ataxia is a reliable and valid measure of ataxia, making it an appropriate primary outcome measure for clinical trials.