OBJECTIVES: SMA is a rare genetic disease characterized by profound physical disability and premature death. When left untreated, this disease leads to very high direct and indirect costs for patients, families, and society. The objective of this study was to quantify the lifetime societal costs and life-years for patients with SMA type 1 (SMA1) who were treated with onasemnogene abeparvovec (OA) or nusinersen in the United Kingdom.

METHODS: We conducted a targeted literature review to identify societal cost elements related to SMA1. This included 1) direct health care costs (for the UK national health services and personal social services), 2) direct non‑health care costs (e.g., expenses for moving, home modification, purchasing or modifying motor vehicles, paid caregivers, and other miscellaneous items [e.g., transportation]), and 3) indirect costs (e.g., family income loss and patient earnings). The societal costs of SMA1 over a lifetime were calculated using a published economic model. This calculation was based on the disease trajectory of treated versus untreated patients, as measured by motor milestone achievement. Future costs and outcomes were discounted at 3.5% per year.

RESULTS: Discounted survival for OA was much greater than for nusinersen (12.8 vs. 8.9 years) and the lifetime societal costs were £68,087 higher (£3,374,801 vs. £3,306,714). These costs included £503,601 and £438,665 non‑health care costs, respectively. As a result, the societal costs per life‑year were £109,387 lower for OA than for nusinersen (£262,740 vs. £372,126).

CONCLUSIONS: Direct and indirect costs associated with SMA1 impose a substantial financial impact on patients, families, and society. This analysis demonstrates that patients treated with OA have a substantially greater life‑expectancy than those receiving treatment with nusinersen. The lifetime cost for an OA-treated patient is slightly greater; however, the cost per life-year is much lower for an OA-treated patient than for a nusinersen-treated patient.