Longitudinal Dosing Patterns and Treatment Costs Among Patients with Spinal Muscular Atrophy Initiating Nusinersen...

Spinal muscular atrophy (SMA) is a neuromuscular disorder historically associated with high morbidity, mortality, and healthcare costs. Disease-modifying therapies have improved outcomes, but their long-term economic burden remains uncertain. Nusinersen and risdiplam, both chronic therapies, differ from onasemnogene abeparvovec, a one-time gene therapy. Understanding real-world treatment costs of chronic SMA therapies is critical to inform therapeutic choice.

This retrospective cohort study used the Komodo Health Research Database (2016-2024). Patients with SMA aged ≥ 2 years who initiated nusinersen or risdiplam were followed up to 5 years. Dosing patterns and drug acquisition and administration costs (2024 USD) were assessed annually, overall and by age group and scoliosis status.

Among 3864 eligible patients, 2743 initiated nusinersen and 1121 initiated risdiplam (mean age 21.4 vs. 25.3 years, respectively; 51.5% vs. 46.1% male). Median follow-up was 5.5 years for nusinersen and 1.1 years for risdiplam. Persistence declined over time, with 39.5% of patients treated with nusinersen and 63.7% of patients treated with risdiplam remaining on their index therapy at years 5 and 4. Patients treated with nusinersen received 3.6 injections on average in year 1 and 2.8-3.1 annually thereafter. Median annualized nusinersen treatment costs were $504,173 in year 1 and $438,788-548,608 in years 2-5. Patients treated with risdiplam had a median of 96 days of supply in year 1 (51.5% with > 90 days); median annualized drug costs were $143,331 overall in year 1 and $259,419 among those with > 90 days of supply, increasing to $264,701-289,340 in years 2-4. Costs were similar across subgroups.

Nusinersen and risdiplam persistence declined over time. Among patients remaining on their index therapy, both treatments had high long-term costs, highlighting the substantial and ongoing financial burden of chronic SMA therapies and the need for real-world evidence to inform healthcare planning.

ClinicalTrials.gov identifier, NCT07378943.