Modeling the Budget Impact of Disease-Modifying Therapies in Infantile-Onset Spinal Muscular Atrophy

Nusinersen, onasemnogene abeparvovec-xioi, and risdiplam are disease-modifying therapies that have demonstrated clinical benefits for patients with spinal muscular atrophy. However, their high costs pose significant challenges for healthcare payers. This study evaluated the potential budget impact of these treatments compared with best supportive care from a US healthcare payer perspective.

A budget impact analysis was conducted over a 5-year time horizon using a state-transition model to estimate direct healthcare costs associated with each disease-modifying therapy and best supportive care in a cohort of children with infantile-onset spinal muscular atrophy. A scenario analysis also assessed the budget impact over a lifetime horizon. Model inputs for transitions and costs were derived from clinical trials, observational registries, and administrative databases.

Compared with best supportive care, the added 5-year per-patient budget impact was $2.18 million for onasemnogene abeparvovec-xioi, $1.51 million for nusinersen, and $1.17 million for risdiplam. When modeled over a lifetime horizon, the incremental per-patient budget impact versus best supportive care was $5.86 million for risdiplam, $3.16 million for onasemnogene abeparvovec-xioi, and $3.05 million for nusinersen.

Disease-modifying therapies for the management of infantile-onset spinal muscular atrophy have a substantial budget impact on US healthcare payers, primarily driven by high drug acquisition costs. The impact (per year) becomes less pronounced when evaluated over a longer time horizon, with the largest lifetime budget impact observed for risdiplam.