Objective: To assess the impact of Friedreich ataxia (FA) on mobility at different modified Friedreich Ataxia Rating Scale (mFARS) ranges.

Background: FA is an autosomal recessive, degenerative disease characterized by decline in mobility and eventual loss of ambulation which have major impacts on quality of life. These disease milestones are assessed by mFARS, however there are limited data on the impact of FA progression on mobility using the FA activities of daily living (ADL) scale, and the correlation between the elements of mFARS and ADL that relate to mobility.

Omaveloxolone slowed disease progression in the MOXIe Part 2 (MOXIe2) trial vs placebo as demonstrated by significant improvement in mFARS scores and a nominally significant improvement (p=0.04) in ADL after 48 weeks. The Friedreich’s Ataxia Clinical Outcome Measures Study (FACOMS) registry provides 13 years of natural history data for patients with FA.

Method: ADL questions about mobility (walking, falling and quality of sitting position) were assessed separately in both the FACOMS and MOXIe2 datasets to determine the proportion of patients with a score at or above the lower bound of selected 10-point mFARS ranges.

Results: In FACOMS, 3 times more patients with a mFARS score of 40-49 were observed to score ≥3 on the ADL walking question (indicating a severe effect on mobility that requires assistance or walking aids) compared to patients with a mFARS score of 30-39 (39% vs. 13%). Similarly, 2.7 times more MOXIe2 patients were recorded with an ADL walking score ≥3 at a mFARS score of 40-49 vs. 30-39 (64% vs. 24%).

In FACOMS, 65% of patients with a mFARS score of 50-59 had a score ≥3 on the ADL falling question (meaning they require an assistive device to prevent falls) compared to 39% of patients with mFARS score of 40-49. This is reflected in MOXIe2, where 58% of patients with a mFARS score of 50-59 had a score ≥3 on the ADL falling question, compared to 38% of patients with a mFARS score of 40-49.

A Spearman’s correlation between the mFARS Upright Stability domain and the sum of ADL mobility questions (6-8) demonstrated correlations of 0.856 and 0.797 (both p< 0.001) in FACOMS and MOXIe2, respectively.

Conclusion: FA is a progressive disease that causes increasing challenges with mobility, as demonstrated for different 10-point mFARS ranges. In both trial and registry data, worsening of ADL scores for mobility-related questions correlated strongly with increases in mFARS scores.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-impact-of-friedreich-ataxia-progression-on-mobility/