Background: Spinal muscular atrophy (SMA) is a neuromotor disease that leads to progressive weakness and paralysis, and prior to disease-modifying therapies (DMTs), caused death in the first two years of life in its infantile onset form. With approval of three DMTs and implementation of newborn screening (NBS) programs, the landscape of the disease has dramatically improved. We sought to examine demographic factors contributing to time to diagnosis and treatment of SMA in a period where therapies were available, prior to NBS.
Methods: This was a retrospective study of patients diagnosed with SMA between January 1, 2017, and April 26, 2020 and followed at the University of Florida. Descriptive statistics (median, range or frequencies and percentages) were computed for patient characteristics.
Results: Nine patients met criteria (5 male), eight of whom had data for time from symptom onset to pediatric neurology referral. 5/8 (63%) had public insurance. 75% were non-Hispanic (NH) white, and 25% were NH black. All but one (NH white) had symptom onset at ≤6 months of age. Median time [range] from symptom onset to referral in this infant cohort was 2 months [0-5] for white infants and 4 months [3-5] in black infants. All patients ultimately received DMT. All patients had initial symptoms of hypotonia, decreased leg movements, and developmental delay. Four reported difficulty breathing and 2 reported difficulty swallowing.
Discussion: In this small retrospective study of patients with SMA, we found the median time from symptom onset to pediatric neurology referral in NH black infants was 2 months higher than NH white infants during a time when DMTs were available. This study is underpowered to have statistical significance but suggests the need for education of this diagnosis amongst primary care physicians, as not everyone opts in to newborn screen.