Objectives The aim of the budget impact analysis (BIA) was to determine the economic impact of introducing risdiplam in the treatment of type 3 spinal muscular atrophy (SMA) patients in a rare diseases reference centre on a 3-year time horizon, as compared with nusinersen.

Methods Public databases were used to estimate the target population. Two market scenarios were assessed over a 3-year time horizon: with nusinersen and with the introduction of risdiplam. Drug acquisition and administration costs were considered. BIA is calculated as the difference between scenarios with nusinersen – scenario with risdiplam.

Results The introduction of risdiplam would generate a 3-year saving of €3411.50. There could be a saving in the administration of risdiplam in the treatment of patients under the age of 2 with a weight of 5 kg (€26 382.08).

Conclusion The BIA shows the overlapping costs of these therapies, although the oral administration of risdiplam could be a decisive factor for the therapeutical switch from nusinersen.