More-Expensive SMA Medication Use Led to Lower Health Care Resource Utilization

A recent study found that patients with spinal muscular atrophy (SMA) treated with newer disease-modifying therapies (DMTs), like onasemnogene abeparvovec, had higher pharmaceutical costs but lower costs for SMA-related health care resource utilization compared with patients who received standard-of-care nusinersen monotherapy.

The study, published in Advances in Therapy, sought to characterize the real-world health care resource utilization (HCRU) and associated costs for US patients with SMA being treated with DMTs, including onasemnogene abeparvovec, nusinersen, and risdiplam.

“The potentially devastating effects of SMA are associated with substantial clinical and economic burdens on patients, families, caregivers, and health care systems, although only a few studies have examined this burden in the real world. Given the evolving treatment landscape of SMA, studies using real-world data that assess outcomes after treatment with DMTs are needed,” wrote the researchers.

Researchers examined medical and pharmacy claims data from the HealthVerity Private Source 20 and 17 (PS20 and PS17) claims databases as well as electronic medical records (EMR), spanning January 1, 2017 to March 31, 2021. The PS20 and PS17 databases contained information on over 155 million and 96 million patients, respectively, and the EMR database included data from over 7000 ambulatory care practices across the United States.

For inclusion, patients had to have a diagnosis for SMA, have at least 1 pharmacy and/or medical claim for 1 of the study drugs, be aged 2 years or younger at the index date, have at least 1 clinical activity in the PS20 database, and have continuous enrollment for between 1 month prior to 2 months after the index date, which was defined as the date of initiation of monotherapy or first treatment switch after the earliest SMA diagnosis. The baseline period was 1 month before the index date, and the study period spanned from the index date to the end of data availability or 1 year of follow-up.

Of the 74 eligible patients, 62 (83.8%) received nusinersen monotherapy and 12 (16.2%) received onasemnogene abeparvovec. No patients receiving risdiplam met the inclusion criteria. Patients treated with onasemnogene abeparvovec tended to be older, male, and have SMA type 2 than those receiving nusinersen (age: 14.2 vs 13.1 years; male: 75% vs 50%; SMA type 2: 58.3% vs 88.7%). Among patients receiving nusinersen monotherapy compared to those in the onasemnogene abeparvovec group, there was a higher prevalence of SMA-related comorbidities, including acute respiratory failure, dysphagia, failure to thrive, and scoliosis. Additionally, among those who received onasemnogene abeparvovec, 9 received it as a monotherapy and 3 received it after switching from nusinersen.

Following weighting, patients treated with nusinersen exhibited higher annual numbers of inpatient visits (mean: 5.3 vs 1.8, respectively) and emergency department visits (mean: 3.0 vs 1.5, respectively; P < .05).

Furthermore, patients in the nusinersen group had greater annual SMA-related medical costs (mean: $78,446) compared with patients treated with onasemnogene abeparvovec (mean: $29,438; mean difference: $49,007; P < .05). Onasemnogene abeparvovec-treated patients incurred higher SMA-treatment pharmacy costs than nusinersen-treated patients (mean: $2,241,875 vs $693,191, respectively; mean difference: $1,548,684; P < .05).

“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,” the researchers noted.

The study relies on retrospective data, introducing potential issues like coding errors and missing key variables. Proxy measures were used, and while propensity score weighting aimed to balance characteristics, residual confounding is possible. Limited data on recently approved therapies led to a focus on the first treatment year, requiring longer follow-up for a complete economic assessment. Assumptions about cost accumulation over time may affect reliability, especially for patients with limited data. Societal costs were not considered, potentially underestimating the overall impact of treatment.

Reference

Toro W, Yang M, Georgieva M, et al. Health care resource utilization and costs for patients with spinal muscular atrophy: Findings from a retrospective US claims database analysis. Adv Ther. 2023;40(10):4589-4605. doi:10.1007/s12325-023-02621-y