Natural History of Type 1 Spinal Muscular Atrophy in a Series of Argentinian Children

Abstract

Background: SMA1 natural history is characterized by early development of chronic respiratory failure. Respiratory interventions in type 1 SMA infants are subject to great practice variability. Nusinersen, has been recently approved in Argentina. The advent of novel treatments has highlighted the need for natural history studies reporting disease progression in type 1 SMA. Objective: To analyze the progression, respiratory interventions and survival based on the type of respiratory support in type 1SMA patients, in a third level pediatric hospital in Argentina. Methods: Cohort of SMA1 patients followed at the Interdisciplinary Program for the Study and Care of Neuromuscular Patients (IPNM). Patient survival was analyzed by using the Kaplan-Meier method. Log-rank test was performed to compare the survival curve for three respiratory intervention groups. Results: 59 patients. Mean age of symptom onset was 2.19 (±1.4) months, age at diagnosis was 3.9 (±2.1) months. Patients developed respiratory failure at 5.82 months (±2.32) and 13.8 months (±5.6) in Type 1B and Type 1C, respectively (p < 0.001) 53 p were SMA1B. Three copies were found in 1/6 SMA1C. Respiratory interventions: SRC 23 p (56.1%); SRC + NIV 8 p (19.5%); SRC + IV 10 p (24.4%). 8 patients were already on invasive ventilation when included in the IPNM. Patients with invasive ventilation showed longer survival. Conclusions: This series provides valuable information on respiratory intervention requirements and life expectancy in children with SMA1 before the implementation of novel treatments that increase the expression of the SMA protein.