Study Details Delays in Spinal Muscular Atrophy Treatment

A new study highlights significant variations in newborn screening practices for spinal muscular atrophy (SMA) across the United States, pointing to potential nationwide changes that could improve the effectiveness of current treatments.

Craig M. Zaidman, M.D.

The research, published in The International Journal of Neonatal Screening, surveyed 30 state newborn screening programs and 41 healthcare providers specializing in SMA care. Led by Craig M. Zaidman, M.D., professor of neurology and professor of pediatrics at Washington University in St. Louis, the study found differences between states that could lead to poorer outcomes for patients.

One of these differences is the timing of confirmatory testing. Some states perform the testing concurrent with initial screening; others defer to the treating provider. Most state programs communicate positive results to both primary care providers and SMA specialists, but some notify only one or the other, which could delay treatment.

All respondents reported seeing SMA patients quickly, most within 72 hours of diagnosis. But many providers couldn’t initiate treatment for weeks due mainly to insurance delays.

“Providers do recognize the urgency of the initial evaluation for newborns with [newborn screening]-identified SMA,” the study authors wrote. “Despite this, many providers cannot initiate treatment until three weeks of life or later.”

Some studies show that infants treated within weeks of birth — before the onset of symptoms — are more likely to achieve normal motor milestones compared with children treated months later. This study noted 66% of respondents reported treating newborns between 2 and 4 weeks of age, with none initiating treatment in less than 1 week on average. The biggest factor providers used to determine whether to start or defer treatment was the presence of symptoms. They also ranked securing insurance approval as the most time-consuming step in initiating treatment.

Newborn screenings for SMA started in the United States in 2018 and has expanded to all 50 states. The Centers for Disease Control and Prevention provide states with quality assurance directives, and each state decides how to implement the program. Untreated, children with the most common form of SMA typically die or become ventilator dependent by age 2. However, quality of life and life expectancy for patients with SMA has greatly improved with the approval of three disease-modifying therapies since 2016.

The International Journal of Neonatal Screening study found Zolgensma (onasemnogene abeparvovec) was the overwhelmingly preferred first-line treatment with 81% of providers choosing that therapy. Spinraza (nusinersen) and Evrysdi (risdiplam) were less commonly picked as initial therapies.

The common prevalence for SMA among newborns is often reported as 1 in 10,000. This study, however, found a slightly lower rate, of 1 in 13,862. False-positive results were infrequent – with 21 states surveyed reporting no occurrences. Among the 364 false positives that were identified, 93% originated in Georgia, where reporting did not differentiate inconclusive screens from true false-positive screens.

“Future efforts focusing on uniform standards for state [newborn screening] program accuracy and efficiency of communications and reducing barriers to timely treatment initiation are most likely to improve the equity of care of infants with SMA,” the authors wrote.