Spinocerebellar Ataxia Progression Measured with the Patient-Reported Outcome Measure of Ataxia.

Background: The Patient-Reported Outcome Measure of Ataxia (PROM-Ataxia) has been validated cross-sectionally but not longitudinally.

Objective: We aimed to validate PROM-Ataxia as a measure of patient experience of disease over time, examine overall and domain-specific progression, and test convergent validity with other clinical outcome assessments (COAs).

Methods: We derived PROM-Ataxia data from 176 patients with spinocerebellar ataxia types 1, 2, 3, 6, 7, 8, or 10 in the Clinical Research Consortium for the Study of Cerebellar Ataxia at baseline and 1 year. We classified patients' ataxia severity stage ("severity") according to the Friedreich's Ataxia Rating Scale Functional Staging into mild, moderate, and severe subgroups. Analyses of the entire cohort and by severity subgroup included internal consistency, sensitivity to disease severity, predictive modeling of score changes, correlations with COAs: Brief Ataxia Rating Scale, Scale for Assessment and Rating of Ataxia, Fatigue Severity Scale, Cerebellar Cognitive Affective Syndrome scale, EuroQol 5-Dimension, and responsiveness to disease progression.

Results: The PROM-Ataxia exhibited high internal consistency and correlated with other COAs. Scores demonstrated sensitivity to disease severity and evolving patient experience. Progression was sigmoidal, with the greatest change in moderate patients. Compared with other COAs, PROM-Ataxia captured the most change. Mental features worsened fastest in mild patients, physical in moderate patients, and activities of daily living in severe patients.

Conclusion: PROM-Ataxia is more sensitive to change than ataxia COAs, captures the evolution of patients' experience of disease over 1 year, and reveals domain-specific progression. Studies of larger cohorts and different ataxia diagnoses over longer periods may provide insights to further enhance clinical care and research. © 2025 International Parkinson and Movement Disorder Society.