The aim of this study is to assess the evolution of respiratory and feeding support in children with spinal muscular atrophy (SMA) type 1 after 24 months of nusinersen treatment.

Data on SMA type 1 children treated with nusinersen between 2017 and 2023 from the Canadian Neuromuscular Disease Registry were extracted. The cohort was divided into two groups based on age at treatment initiation: ≤2 years and >2 years. The primary outcome was the (i) time to death or needing full-time (≥16 hours/day) ventilation and (ii) time to needing feeding tube support. The secondary outcomes were differences in respiratory and feeding support requirements between the two groups at 24-month follow-up.

Thirty-two children were included, and the median age (range) for treatment initiation was 3.2 months (0.8– 13.1) in children who initiated treatment at ≤2 years and 51.2 (28.7–183.8) in those who initiated at >2 years of age. The median age of death or full-time ventilation was 8.6 months (6–22.4) and 10.5 months (4–24) for the two groups, respectively. The median age for initiation of feeding support was 5.1 (1.7–26.4) and 14.5 months (3.9–130.6), respectively. At 24 months (n = 23), there were no significant differences between the need for respiratory or feeding tube support between the two treatment groups.

Most children with SMA type 1 treated with nusinersen across Canada have continued need for respiratory and feeding support over time when initiated after symptom onset.