Health Care Resource Utilization, Cost Vary by SMA Therapy, Analysis Shows

The data show how disease-modifying therapies are changing outcomes for children with spinal muscular atrophy (SMA), a rare neuromuscular disease.

A new analysis of the real-world outcomes of young children with spinal muscular atrophy (SMA) suggests the use of onasemnogene abeparvovec (Zolgensma) leads to lower health care resource utilization (HCRU) compared with nusinersen (Spinraza).

However, the data also show that patients receiving onasemnogene abeparvovec had higher overall health care costs than patients taking nusinersen, due to higher pharmacy costs. The report was presented as a poster at the Academy of Managed Care Pharmacy’s 2023 annual meeting.

The study authors explained that SMA, a rare genetic neuromuscular disease caused by the deletion or mutation of the SMN1 gene, had been the leading genetic cause of infant mortality prior to the development of disease-modifying therapies (DMTs). However, in 2016, the FDA approved the antisense oligonucleotide nusinersen to treat SMA. That therapy, along with the subsequent approvals of the gene-replacement therapy onasemnogene abeparvovec in 2019 and the small molecule SMN2-directed RNA-splicing modifier risdiplam (Evrysdi) in 2020 have led to significant improvements in the prognosis of patients with the disease.

Yet, despite strong clinical trial data and successful usage of the therapies, there has been little in the way of scientific literature tracking how the therapies have affected health care utilization.

The investigators consulted a database of medical claims to identify patients aged 0 to 2 years with SMA who received 1 of the 3 approved therapies between January 2017 and March 2021. Sixty-two patients taking nusinersen monotherapy were identified and met inclusion criteria. Twelve patients taking onasemnogene abeparvovec were found; 9 were taking it as monotherapy and 3 patients took the therapy after nusinersen. No patients on risdiplam met the study’s inclusion criteria.

Patients who were taking onasemnogene abeparvovec were more likely to be older at the study’s index date and when they received their diagnosis. They were also less likely to be female or to have type 2 SMA. SMA is categorized based on age of onset and severity; type 1 is the most severe form.

The study authors used propensity score weighting to account for differences in baseline characteristics between the 2 treatment groups. However, the investigators found patients receiving nusinersen had higher HCRU both before and after weighting.

All of the patients were followed for at least 2 months prior to the index date. After weighting, the investigators calculated the cost of health care provider visits, hospital care, and skilled nursing to be an average of $78,446 on an annualized basis for people taking nusinersen monotherapy vs $29,438 for patients receiving omnasmnogene abeparvovec.

The data showed that patients in the nusinersen monotherapy group were more likely than patients taking onasemnogene abeparvovec to have spent time as a hospital inpatient (72.9% vs. 48.1%), visited the emergency department (70.5% vs. 69.0%), spent time in a skilled nursing facility (10.0% vs. 0.0%), or received skilled nursing in-home visits (5.7% vs. 0.0%).

Conversely, patients taking onasemnogene abeparvovec had significantly higher overall health care costs compared with patients taking nusinersen monotherapy, the investigators found, due to differences in the cost of the therapies themselves.

“Patients treated with nusinersen monotherapy incurred significantly lower SMA treatment costs than those treated with onasemnogene abeparvovec, with a mean difference of $1,548,684 after weighting (P < .05),” they said.

The authors noted that the time frame of their data set included years when nusinersen was the only approved therapy for SMA, and as such, most patients included in the study were taking nusinersen. Although their study offered a first look at real-world health care utilization in the era of DMTs, they said additional studies will be needed to better understand how the new therapies affect the economics of treating these patients over the long term.


Toro W, Yan M, Georgieva M, et al. Treatment patterns and outcomes in patients with spinal muscular atrophy: real-world findings of a retrospective US claims database analysis. Poster presented at: AMCP 2023; March 21-24, 2023; San Antonio, TX.

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