July 20, 2024

Screening newborns for spinal muscular atrophy (SMA) can significantly improve health outcomes when treatment is begun immediately, compared to infants who are diagnosed and treatment only months later, according to a study published in JAMA Pediatrics.

SMA, a genetic disorder that causes muscle weakness and atrophy due to motor neuron loss in the spinal cord, affects approximately 1 in 10,000 newborns who are typically diagnosed within the first year of life as development delays become apparent.

Untreated, children with the most common form of SMA typically die or become ventilator dependent by age 2. However, the approval of three disease-modifying therapies since 2016 has greatly improved quality of life and life expectancy for patients with SMA.

While clinical trials have demonstrated that treating children before the onset of symptoms can lead to age-appropriate motor development, a direct comparison with children diagnosed and treated later was lacking. The study’s researchers wanted to measure outcome differences between the two groups, and analyzed 234 children diagnosed with SMA across Austria, Germany and Switzerland.

The study found that early intervention led to much better outcomes. Infants diagnosed through newborn screening started treatment on average at 1.3 months old, compared to 10.7 months for the group diagnosed after symptoms appeared. As a result of the early treatment, 91 percent of the newborn screening group achieved the ability to sit independently, compared to 74 percent of the later-diagnosed group. More remarkably, 64 percent of the early diagnosed group were able to walk independently, compared to only 15 percent of their counterparts.

“This study provides evidence in support of newborn screening for SMA in a nonrandomized, controlled cohort design,” the study authors wrote. “Patients identified by newborn screening showed better motor development, less need for ventilator support and tube feeding, and less disease burden.”

The disease modifying therapies approved by the FDA include Spinraza (nusinersen), Evrysdi (risdiplam) and Zolgensma (onasemnogene abeparvovec-xioi). The study did not examine if any of the three treatments were superior.

JAMA Pediatrics published the study, “Clinical Effectiveness of Newborn Screening for Spinal Muscular Atrophy: A Nonrandomized Controlled Trial,” online on April 8, 2024.

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