BACKGROUND & OBJECTIVES: Early, pre-symptomatic treatment of spinal muscular atrophy (SMA) with disease-modifying therapy improves outcomes. In the United States (US), newborn screening (NBS) for SMA is recommended and is implemented at the state level. We analyzed the processes and experiences of states currently performing NBS for SMA.
METHODS: We surveyed participating US states regarding methodologies of NBS for SMA including laboratory techniques, reporting and confirmation of results, follow-up, and outcomes.
RESULTS: As of December 2021, 24 state NBS offices responded, with missing data excluded. The majority of states conduct SMA screening in the state-run laboratory (14/23, 61%). Few contract NBS to private (5/23, 22%) or academic (4/23, 17%) laboratories. Most use real-time quantitative PCR (18/21, 86%). The infant’s physician typically performs SMA confirmatory testing and reports results to the NBS office (20/24, 83%). False positive SMA NBS results were generally rare but varied by state. No state reported false negatives. Processes for reporting and follow-up of positive SMA results varied by state. Most states report positive results directly to the primary care provider (PCP) and a subspecialist (18/24, 75%), fewer report to PCP (2/24, 8%) or subspecialist (4/24, 17%) alone. Nearly half (11/24, 46%) of laboratories report survival motor neuron 2 copy number. Most states perform short-term follow-up of screen positive infants (21/23, 91%) including tracking referral to a specialty provider and confirmation of diagnosis. Few NBS offices perform standardized long-term follow-up (4/19, 21%). Participation in national newborn screen tracking databases also varied by state.
CONCLUSIONS: Newborn screening for SMA varies by state at multiple levels, including test methodology, response to positive screens, and follow-up of outcomes. Additional study is needed to determine if these variations impact time to treatment. This could help develop guidelines to optimize the care of infants with SMA. Data collection and analysis is ongoing.