Economic burden shifting in US after arrival of SMA treatments
Overall, healthcare costs tend to be lower for patients now than in pre-DMT era
Children with spinal muscular atrophy (SMA) treated with Zolgensma (onasemnogene abeparvovec) used fewer healthcare resources and had lower medical costs than children on Spinraza (nusinersen), but they had higher SMA treatment costs, according to a recent U.S. analysis.
Overall, healthcare costs for SMA patients using these disease-modifying therapies (DMTs) were lower than those reported prior to the availability of specific SMA-targeted therapies.
“Future studies to examine SMA treatment patterns as the clinical landscape continues to evolve, and to evaluate the long-term economic burden associated with SMA management, are recommended,” researchers wrote.
The study, “Health Care Resource Utilization and Costs for Patients with Spinal Muscular Atrophy: Findings from a Retrospective US Claims Database Analysis,” was published in Advances in Therapy and funded by Novartis, which markets Zolgensma.
SMA requires lifelong treatment and substantial medical care
A chronic, neuromuscular disease, SMA is caused by mutations in the SMN1 gene, leading to a lack of the SMN protein that’s needed for the health of nerve cells involved in motor function.
SMA requires lifelong treatment and substantial medical care, leading to a high usage of healthcare resources that places significant economic burden on patients, their families, and the healthcare system.
The treatment landscape of SMA has dramatically evolved in the last decade, with three DMTs now available. Spinraza and Evrysdi (risdiplam) are lifelong treatments that aim to boost the body’s production of SMN by increasing the activity of the “backup” SMN-producing gene, SMN2.
Zolgensma, a one-time gene therapy, provides patients with a working version of the SMN1 gene, enabling the body to produce a working SMN protein.
It has not been well-established how each of these therapies have influenced healthcare resource utilization and associated costs for SMA patients in the U.S.
To address this, researchers at Novartis and the Analysis Group analyzed insurance claims and electronic medical record data from the U.S. HealthVerity claims database, from January 2017 to March 2021.
Patients were included if they had a verified SMA diagnosis, were either started on any SMA DMT or switched to another by age 2, and had follow-up data of two months or more.
A total of 74 patients met the criteria, including 62 (83.8%) treated with Spinraza, and 12 (16.2%) treated with Zolgensma. The latter group included nine patients who received Zolgensma alone and three who switched to it from Spinraza.
No Evrysdi-treated patients met the inclusion criteria, which researchers attributed to the therapy’s more recent approval date (mid-2020) for children with SMA.
Patients followed up for 1 year
In both Spinraza and Zolgensma groups, patients were followed up for a median of one year. Because there were some demographic and clinical differences between the groups, healthcare data were adjusted, or weighted, to account for sex, SMA type, and SMA-related comorbidities, or simultaneous conditions.
Results showed that healthcare resource utilization was generally higher among patients treated with Spinraza alone compared with those given Zolgensma, although not all categories reached statistical significance after weighting.
Still, Spinraza-treated patients experienced a significantly higher average number of annual visits to the emergency department compared with those in the Zolgensma group (three vs. 1.5 visits).
The annual number of inpatient visits was also higher in the Spinraza group (5.3 versus 1.8), but the difference was not statistically significant after weighting.
In terms of costs, Spinraza-treated patients generally incurred significantly greater medical care costs than the Zolgensma group. While the Spinraza group had average annual SMA-related medical costs of $78,446, costs in the Zolgensma group were $29,438 — an annual difference of $49,007.
This difference was primarily driven by significantly lower costs associated with inpatient and emergency department visits in the Zolgensma group. In addition, significantly more was spent on ventilation support, nutrition support, and mobility braces for Spinraza patients.
“The greater medical costs among children treated with [Spinraza] may be explained by greater use of invasive procedures [for respiratory and nutrition support] in inpatient settings as well as unobserved or unbalanced patient characteristics between the two treatment groups,” the researchers wrote.
Findings reflect ‘common theme of the costliness of this disease’ in US
In turn, overall SMA treatment costs were significantly higher at an average of $2,241,875 for the Zolgensma group, compared with $693,191 for those on Spinraza alone.
This resulted in a significantly greater total annual costs (medical and pharmacy) for Zolgensma-treated patients ($2,271,313 vs. $771,637) — a mean difference of $1,499,676.
Overall, “high [healthcare resource utilization] and health care costs associated with SMA reflect a common theme of the costliness of this disease as reported in previous US-based studies,” the researchers wrote.
The scientists noted that these estimates of SMA medical costs tended to be lower than those previously reported in the pre-DMT era.
“Our findings indicate that treatment with DMTs manages SMA symptom progression and reduces the associated economic burden, as reflected in lower inpatient and outpatient costs,” they wrote.
Because patients were followed for up to one year only, longer studies will be needed to better understand long-term economic effects of DMT use in SMA patients, the team concluded.