Minimal Clinically Important Difference of the Scale for the Assessment and Rating of Ataxia

Background The Scale for the Assessment and Rating of Ataxia (SARA) is the most used outcome measure in clinical trials for cerebellar ataxias. The minimal clinically important difference (MCID), a parameter used to assess meaningful change, is not clearly defined. Objective To help define MCID for SARA. Methods Sixty‐two individuals with cerebellar ataxias participated in a home‐exercise clinical trial. Participants had outcomes assessed [SARA, Timed Up and Go (TUG), Dynamic Gait Index (DGI), gait speed, Patient Global Impression of Change (PGIC)] at 0‐, 6‐, 9‐, and 12‐months. Three methods were used to determine the MCID for SARA: anchor‐based method, distribution‐based method, and distribution‐based mapping. Results The MCID for SARA using anchor‐based method was 1.75. The distribution‐based method and distribution‐based mapping identified a median MCID score of 1.23. Conclusion Synthesizing methods, we determined an MCID of 1.5 points. An accurate MCID is critical to ensure future treatments are clinically relevant.