OBJECTIVES: Spinal muscular atrophy (SMA) is a rare, genetic, neuromuscular disease associated with progressive, irreversible motor neuron loss that results in muscle atrophy leading to progressive muscle weakness and paralysis, impairment of swallowing and breathing and premature death in its most severe form (SMA-type-1 which accounts for approximately 58% of SMA incident cases). Until the introduction of the first treatment for SMA in 2017, more than 90% of infants affected by SMA-type-1 died or required permanent ventilation by the age of two. The changing treatment landscape did potentially have an impact on estimates of SMA epidemiology, leading to uncertainty for health care authorities when making resource allocation decisions. The objective of this analysis was to understand the current SMA epidemiology in Italy, focusing on SMA type and age.

METHODS: In addition to a literature search, data were collected in the period from May 2019 to April 2020 in approximately 80% of Italian SMA pediatric centers via physician interviews and questionnaires and from hospital registries. Experts in SMA and patient associations validated the results.

RESULTS: Currently, the estimated number of SMA patients in Italy is 850, corresponding to a prevalence of 1.41 per 100,000 inhabitants. This number, confirmed by patient associations, is likely underestimated due to the lack of follow up of patients with less severe forms. Of these, 650 patients (>75%) are being treated in pediatric centers. 210 of all patients are affected by SMA-type-1, with a median age of about 4.5 years. It is a common and very strong perception that clinical outcomes particularly in SMA-type-1 patients treated with new therapeutic agents, including gene replacement therapy, may conduct to unprecedented survival leading to an evolution of SMA epidemiology

CONCLUSIONS: SMA patient outcomes are changing and with the upcoming new therapies we expect that health authorities will need to consider evolving epidemiologic data.