OBJECTIVES: To estimate the cost of care among infantile and child spinal muscular atrophy (SMA) patients in a large US database.

METHODS: This retrospective study estimated the cost of care (2021 USD) for patients newly diagnosed with SMA (ICD-10-CM: G12.0, G12.1, G12.8, G12.9) between Jan01, 2017, and Dec31, 2021 in CHRONOS, an integrated closed and open claims database. Patients first diagnosed with SMA (index event) between 0-12-months or between 13-36-months of age were defined as infantile SMA (iSMA) or child SMA (cSMA), respectively. Patients with an infantile diagnosis (G12.0) first recorded after 12-months of age or patients with juvenile SMA were excluded. Costs were calculated from patient and insurer payments recorded on institutional, professional, and pharmacy claims. Mean costs per-patient-per-month (PPPM) are reported from index through the end of enrollment or 12-months of follow-up.

RESULTS: Patients with iSMA(n= 118) and cSMA(n=63) were 7- and 20-months years old at index and 53% and 62% male, respectively. Patients were diagnosed in inpatient (46% of iSMA; 21% of cSMA), outpatient (52% of iSMA; 76% of cSMA), and ER (2% of iSMA; 3% of cSMA) settings. Gene therapy (GT) was received by 35% and 24% of iSMA and cSMA patients. 31% of iSMA patients received GT in the first 3-months of care. The mean cost PPPM was $159,979 among iSMA patients and $60,150 among cSMA patients. Excluding GT, the mean cost PPPM was $40,640 among iSMA patients and $37,888 among cSMA patients. Costs were higher in inpatient than outpatient and ER settings.

CONCLUSIONS: GT and other recently approved SMA therapies contribute substantially to the cost of care and were accrued in the 1-3 months of care for iSMA patients but were evenly distributed over the follow-up for cSMA patients. Further research will examine the effectiveness of these novel therapies in a real-world setting.