March 22, 2021
Illness costs resulting from spinal muscular atrophy (SMA) vary widely across disease phenotypes and geographical settings, according to a systematic literature review published online ahead of print in the journal Applied Health Economics and Health Policy.
“There are several phenotypes of SMA,” researchers explained, “from SMA type I (Werdnig–Hoffmann disease) to SMA type IV (adult-onset SMA), with stark differences in onset and severity.”
SMA type I tends to be most severe, with death or permanent ventilation support needed within 12 months or less, according to the study. SMA types III or IV, on the other hand, typically does not affect lifespan but can impair functional ability, such as walking.
The systematic review included 14 studies from eight countries: Australia, France, Germany, Italy, Spain, Sweden, the United Kingdom, and the United States. Studies reported on direct medical, direct nonmedical, and indirect costs associated with any SMA phenotype. Researchers converted all cost findings to 2018 US dollars.
The findings revealed considerable variability between studies. For instance, average per-patient annual direct medical cost of illness estimates ranged between $3320 for SMA type III in Italy to $324,410 for SMA type I in the United States, according to the review.
Average per-patient annual direct nonmedical cost estimates ranged between $25,880 for SMA types I through III in Spain to $136,800 for SMA type I in Sweden. Finally, average per-patient annual indirect cost estimates spanned $9440 for SMA type I in Germany through $74,910 for SMA type II in Australia.
The wide variability reflects, in part, differences in the various studies, noted researchers. They pointed out that while one investigation categorized inpatient care, outpatient care, emergency care, prescription and over-the-counter medications, medical devices and aids, and copayments as direct medical costs, another limited direct medical costs solely to inpatient, outpatient, and emergency care.
“For these reasons, cost estimates are typically not directly comparable between studies, in particular if conducted in different geographical settings,” researchers advised. “That being said, the range in direct medical costs identified as part of this review was still somewhat surprising.”
Nevertheless, the results are relevant in light of emerging SMA treatments, researchers advised, and communicate “the substantial unmet medical need in this patient population.”
Landfeldt E, Pechmann A, McMillan HJ, Lochmüller H, Sejersen T. Costs of Illness of Spinal Muscular Atrophy: A Systematic Review [published online ahead of print, 2021 Feb 12]. Appl Health Econ Health Policy. 2021;10.1007/s40258-020-00624-2. doi:10.1007/s40258-020-00624-2