Higher Health Care Costs and Utilization for Infantile-Onset SMA

Patients with spinal muscular atrophy (SMA) incur significant health care resource utilization and cost burden, particularly those with infantile-onset SMA. Research published in Journal of Health Economics and Outcomes Research provides a baseline on care patterns and costs because it was conducted prior to the approval of the first treatment for SMA.

Researchers conducted the retrospective study using patients with SMA who were identified from the HealthCore Integrated Research Database between January 1, 2006, and March 31, 2016. Nusinersen (Spinraza) was the first disease-modifying therapy approved for SMA, which the FDA approved in December 2016. Since then, 2 other therapies, including the oral, at-home therapy risdiplam (Evrysdi).

SMA is classified according to age of onset and degree of disability. SMA I is the most severe type and is typically diagnosed before 6 months age. These infants are unable to sit unsupported and if the disease is left untreated, they will suffer respiratory insufficiency and die within the first 2 years.

“The emergence of new treatments is changing the management and cost burden of SMA,” the authors wrote. “Assessment of the value of these new, potentially high-cost treatments requires a solid baseline understanding of the disease-related complications, supportive care, and associated medical costs.”

The researchers matched patients without SMA to patients with SMA on a 1:1 basis based on birth year and month, gender, health plan type, region, and health plan subscriber status. There were 341 pairs of patients: 23 were in the infantile cohort (index fate before the age of 6 months), 22 in the childhood-onset cohort (index fate between the ages of 6 months and 3 years), and 296 in the late-onset cohort (index date after 3 years).

The patients were followed from the index date until either the end of the study period, the end of health plan eligibility, or death. The mean length of follow up was 11.0 months in the infantile cohort, 27.7 months in the childhood-onset cohort, and 36.0 in the late-onset cohort.

During follow-up, patients in the infantile cohort were most frequently prescribed acid suppressants and antibiotics (56.5% each), while patients in the childhood- and the late-onset cohorts were most commonly prescribed antibiotics (68.2% and 67.2%, respectively). Patients in the childhood- and late-onset cohorts were also frequently prescribed muscle relaxants (31.8% and 36.8%) and benzodiazepines (31.8% and 36.1%). Patients in the late-onset cohort were also frequently prescribed antidepressants (31.8%).

While hospitalizations and office visits were higher among patients with SMA than those without SMA, patients with SMA in the infantile cohort had the highest proportion (91.3%), followed by those in the childhood-onset cohort (50.0%), and then the late-onset cohort (37.2%).

Total mean health care costs were also highest in the infantile SMA cohort on a per-patient-per-month basis (mean $25,517). Costs were significantly lower for the childhood-onset cohort (mean $6357) and the late-onset cohort ($2499). In comparison, total mean health care costs in among the non-SMA cohorts was highest among the late-onset cohort (mean $742).

According to the authors, the total health care costs reflected the different needs of the cohorts. For patients in the infantile cohort, inpatient hospitalizations accounted for the bulk of the costs; however, for the childhood-onset cohort, prescription medication costs accounted for most of the costs.

Since the study predated the first approved therapy for SMA, the patients did not receive any treatment, and an updated analysis needs to be conducted to better understand the current burden of illness for SMA.

“An updated burden of illness analysis, reflecting the use of new treatment in patients with SMA and specifically patients with different SMA subtypes, will be needed to understand the impact of new treatment on patient outcomes, care delivery, and costs in the healthcare systems,” the authors wrote. “This study could be used as a reference point for future research.”

Reference

Tan H, Gu T, Chen E, Punekar R, Shieh PB. Healthcare utilization, costs of care, and mortality among patients with spinal muscular atrophy. J Health Econ Outcomes Res. 2019;6(3):185-195. doi:10.36469/63185