Six‐minute walk test as outcome measure of fatigability in adults with spinal muscular atrophy treated with nusinersen

Introduction/Aims Fatigue (subjective perception) and fatigability (objective motor performance worsening) are relevant aspects of disability in individuals with spinal muscular atrophy (SMA). The effect of nusinersen on fatigability in SMA patients has been investigated with conflicting results. We aimed to evaluate this in adult with SMA3. Methods We conducted a multicenter retrospective cohort study, including adult ambulant patients with SMA3, data available on 6‐minute walk test (6MWT) and Hammersmith Functional Motor Scale—Expanded (HFMSE) at baseline and at least at 6 months of treatment with nusinersen. We investigated fatigability, estimated as 10% or higher decrease in walked distance between the first and sixth minute of the 6MWT, at baseline and over the 14‐month follow‐up. Results Forty‐eight patients (56% females) were included. The 6MWT improved after 6, 10, and 14 months of treatment (p