Health Care Resource Utilization and Costs for Patients with Spinal Muscular Atrophy: Findings from a Retrospective US Claims Database Analysis

IntroductionSpinal muscular atrophy (SMA) is a neurogenic disorder associated with progressive loss of muscle function, respiratory failure, and premature mortality. This study aimed to describe and compare real-world health care resource utilization (HCRU) and costs for US patients with SMA treated with disease-modifying treatments, including onasemnogene abeparvovec, nusinersen, and/or risdiplam.MethodsThis study used claims and structured electronic medical record data from the HealthVerity claims database (January 1, 2017-March 31, 2021). Eligible patients were aged & LE; 2 years at index (treatment initiation or switch), diagnosed with SMA, had & GE; 1 pharmacy/medical claim for onasemnogene abeparvovec, nusinersen, and/or risdiplam, and continuous enrollment & GE; 1 month pre- and & GE; 2 months post-index. SMA-related HCRU and costs during the study period (> 12 months post-index) were compared between treatment groups before and after propensity score weighting. Costs were adjusted to 2021 USD.ResultsOf 74 included patients, 62 (83.8%) received nusinersen and 12 (16.2%) received onasemnogene abeparvovec (monotherapy, n = 9; onasemnogene abeparvovec after nusinersen [switching], n = 3). After weighting, nusinersen-treated patients had greater annual numbers of inpatient (mean 5.3 nusinersen vs. 1.8 onasemnogene abeparvovec) and emergency department (mean 3.0 nusinersen vs. 1.5 onasemnogene abeparvovec; p < 0.05) visits, and greater annual SMA-related medical costs (mean $78,446 nusinersen vs. $29,438 onasemnogene abeparvovec; mean difference $49,007, p < 0.05) than onasemnogene abeparvovec-treated patients. Onasemnogene abeparvovec-treated patients incurred greater SMA-treatment pharmacy costs than nusinersen-treated patients (mean $2,241,875 onasemnogene abeparvovec vs. $693,191 nusinersen; mean difference $1,548,684, p < 0.05).ConclusionsSMA is associated with substantial economic burden. Patients treated with onasemnogene abeparvovec had greater SMA treatment-related pharmacy costs but lower SMA-related HCRU and medical costs compared with patients receiving nusinersen monotherapy. Plain Language SummarySpinal muscular atrophy (SMA) is a crippling neurodegenerative disease with symptoms of respiratory failure, muscle weakness and loss of function, and premature death. This study describes and compares real-world health care resource utilization (HCRU) and costs for US patients with SMA receiving current treatments (e.g., onasemnogene abeparvovec, nusinersen, risdiplam) using claims and electronic medical record data from a US claims database. Patients included (n = 74) in the study were & LE; 2 years old at treatment initiation/switching of treatments (index), had been diagnosed with SMA and had one or more pharmacy or medical claim for onasemnogene abeparvovec, nusinersen, or risdiplam, and were continuously enrolled for & GE; 1 month before and & GE; 2 months after index. SMA-related HCRU and costs during the study period (up to 12 months post-index) were compared between treatment groups before and after propensity score weighting, with costs adjusted to 2021 USD. Propensity score weighting allows better comparison between patients in treatment and comparison groups by assigning patients different "weights." This weighting allows investigators to be certain that differences in outcomes between patient groups are a result of a particular treatment. After weighting, nusinersen-treated patients had a greater number of inpatient and emergency department visits and greater SMA-related medical costs annually, whereas patients who received onasemnogene abeparvovec had greater pharmacy costs. Our study indicates the greater medical costs among patients receiving nusinersen were largely driven by invasive procedures, such as tracheostomy and gastrostomy, that required hospitalization, but the exact mechanism of greater HCRU/costs associated with nusinersen needs to be further assessed.