Researchers discovered through a retrospective claims database analysis that the rate of discontinuation and nonadherence to nusinersen was relatively high among spinal muscular atrophy (SMA) patients, according to a study published in Advances in Therapy.

The discontinuation and nonadherence were associated with higher incidences of SMA-related comorbidities, as well as increased healthcare utilization and costs. 

“The indicated dosing regimen of nusinersen requires lifelong intrathecal injections every 4 months following the first four injections, administered during the loading phase,” the research team wrote. The intrathecal form of administration may be burdensome to some patients.

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“Because little real-world data exist for adherence to nusinersen treatment, we examined dosing patterns for patients with SMA types 1, 2, or 3 treated with nusinersen in the United States,” the researchers explained.

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They collected data from a longitudinal patient data source, which provided information on prescription claims, the use of medical resources, and healthcare costs across the United States. They included patients who were diagnosed with SMA type 1 (n=23), type 2 (n=41), or type 3 (n=260) and were subsequently initiated on nusinersen therapy after its December 23, 2016 approval by the US Food and Drug Administration

The data collected allowed researchers to determine if and when discontinuation and nonadherence occurred, and their impact on comorbidities, healthcare resource utilization, and healthcare costs. Various studies have demonstrated that nonadherence to prescribed medications can add a significant burden to healthcare systems.

“Deviations from the indicated nusinersen treatment schedule were frequent in real-world usage, with most patients receiving ≥1 dose outside the scheduled interval,” the researchers reported.

SMA patients who did not adhere to their nusinersen treatment were more likely to have SMA-related comorbidities, such as respiratory anomalies, feeding difficulties, and muscle weakness. Across SMA types, the discontinuation of nusinersen was associated with higher healthcare costs. 

While this study investigated the effects of nonadherence of nusinersen on clinical outcomes and costs, the researchers suggested that future studies look into the effects of nusinersen adherence on similar parameters. “Future research would also be important to evaluate adherence to other treatments for SMA that became available after the completion of this work,” they added. 


Gauthier-Loiselle M, Cloutier M, Toro W, et al. Nusinersen for spinal muscular atrophy in the United States: findings from a retrospective claims database analysisAdv Ther. Published online October 28, 2021. doi:10.1007/s12325-021-01938-w