SMA Costs Vary Widely Around the World by Disease Type

Reliable data on the costs of spinal muscular atrophy (SMA) illness are scarce, leaving key questions unanswered as new, high-priced therapies continue to alter the landscape, according to a newly published literature review.

In a study published in Applied Health Economics and Health Policy, a database search found just 14 studies from 8 countries with significant data; the remainder generally lacked relevant cost figures. The results that were seen revealed a wide range of costs based on the country in which the study was conducted and disease phenotype.

The mean per-patient annual direct medical cost was estimated at between $3320 (SMA type 3) in Italy and $324,210 (type 1) in the United States, with the variability high for other measures as well. The mean per-patient annual indirect cost ranged from $9,400 (type 1) in Germany to $74,910 (type 2) in Australia to $136,800 (type 1) in Sweden.

No previous study has systematically reviewed the literature for cost estimates related to SMA, the authors said.With the advent of new drugs such as nusinersen (Spinraza), which is designed to treat the underlying chromosomal defect, and onasemnogene abeparvovac-xioi (Zolgensma), a gene replacement therapy available in a 1-shot intravenous dose, the authors sought to provide information to allow for evidence-based financial choices, they wrote. Other possible treatments, such as splice-modifying therapies, may be on the horizon as well.

SMA is a rare inherited disease characterized by progressive muscle degeneration. There are several phenotypes of the disease, ranging from SMA type 1 (Werdnig-Hoffman disease) to type 4 (adult onset). Type 1, the most severe, occurs at birth or in infancy; death or the need for a permanent ventilator occurs at a median age of less than 12 months. Patients with SMA types 3 and 4 typically have a normal lifespan despite significant loss of function.

The overall prevalence of SMA overall has been estimated at 1 to 2 per 100,000 individuals, with an incidence of approximately 1 in 10,000 live births.

The database search identified studies in Australia, France, Germany, Italy, Spain, Sweden, the United Kingdom, and the United States. Wide variation in data from the studies stemmed from differences in scope, measured quantities of included resources, and price/unit costs.

As expected, SMA type 1 costs were highest due to the need for 24-hour care and ventilation. When accounting for the cost of nusinersen, the per-patient annual direct medical cost was estimated at $1,000,289 (type 1) and $1,190,060 (types 2-4).

A study in the United Kingdom found a per-patient annual hospitalization cost of $129,100, which aligned with the authors’ literature review. Another study found that nusinersen resulted in lower per-patient annual direct costs for SMA type 1 compared with conventional therapy ($92,620 vs $137,630), but not type 2‑3 ($76,370 vs $49,180). The authors said such findings suggest nusinersen warrants further research.

The identified studies did indicate that direct nonmedical costs (informal care and disease-related costs for personal assistants, travel expenses, legal advice, house/car modifications) made up an average of 68% of the per-patient annual total direct cost, ranging from 21% in Australia (type 1) to 86% in Germany (types 1-3). The findings correlated with estimates regarding other neuromuscular diseases such as Duchenne muscular dystrophy (47%-73%).

The authors noted that several studies in their literature review were at risk of bias due to incomplete reporting, documentation, and/or stratification.

Reference

Landfeldt E, Pechmann A, McMillan HJ, Lochmüller H, Sejersen T. Costs of Illness of spinal muscular atrophy: a systematic review. Appl Health Econ Health Policy. Published online February 12, 2021. doi:10.1007/s40258-020-00624-2