INTRODUCTION: The Friedreich Ataxia Rating Scale-Activities of Daily Living (FARS-ADL) is a valid, highly utilized measure for assessing ADL impacts in patients with Friedreich ataxia. We provide evidence of the psychometric validity of the FARS-ADL in two cohorts of patients with spinocerebellar ataxia (SCA). METHODS: Using data from a cohort of real-world subjects with SCA (recruited at Massachusetts General Hospital [MGH]
n = 33) and a phase 3 trial of troriluzole in adults with SCA (NCT03701399 [Study 206]
n = 217), comprising a subset of patients with the SCA3 genotype (n = 89), the psychometric measurement properties and minimal change thresholds of the FARS-ADL were examined. RESULTS: Ceiling effects for the FARS-ADL were absent within the MGH cohort while floor effects were observed for eight of nine items. Excellent internal consistency reliability was observed (α CONCLUSION: Psychometric evaluation showed that the FARS-ADL performed well on analyses examining the reliability and validity of the measure and can detect meaningful changes in patients with SCA, including those with SCA3. TRIAL REGISTRATION: ClinicalTrials.gov identifier, NCT03701399 (Study 206).