Exploring the clinical meaningfulness of the Scale for the Assessment and Rating of Ataxia: A comparison of patient and physician perspectives at the item level

Background: The Scale for the Assessment and Rating of Ataxia (SARA) is commonly used as the primary outcome measure in therapeutic trials. Driven by spontaneous comments from ataxia patients participating in a trial, we aimed to examine the clinical meaningfulness of the SARA from their perspective. Methods: Twenty mildly to moderately affected individuals with spinocerebellar ataxia type 3 (SARA score 11.3 +/- 4.1) completed a custom-designed survey. SARA item scores were compared with self-reported complaints in everyday life. Discrepancies between SARA ratings and patients' daily life experiences were reported as "over -estimation" (i.e., a SARA item score more than 0, but no corresponding complaints) or "underestimation" (i.e., a SARA item score of 0, yet accompanying complaints). Results: Patient-physician discrepancies were present in essentially all SARA items except for gait. The mean number of overestimated SARA points per patient was 3.1 +/- 2.1. Underestimation occurred less frequently, but was relatively common in stance and fast alternating hand movements. Three quarters of patients marked gait as the most valuable SARA item, while the remaining 25% selected stance. Conclusion: On average, a quarter of total SARA score does not reflect meaningful impairments from a patient's perspective. Our data suggest that it is doubtful whether potential improvements at some of the items will be perceived as comparably important by mildly to moderately affected ataxia patients. These observations question the utility of delta SARA score as the most appropriate primary endpoint in clinical trials and call for the addition of outcome measures, such as the Patient Global Impression of Change scale and validated ataxia-specific patient-reported outcome measures.