133P Description of UK SMA cohorts since the introduction of disease modifying therapies

The incidence of Spinal Muscular Atrophy (SMA) has historically been significantly impacted by the high mortality rate that affected the most severe phenotype of the disease. Patients with SMA type I, expected to be 60% of the cases of children born with SMA, have experienced an increase in survival rate since the introduction of disease modifying therapies (DMT) and there is a subsequent increase in the prevalence of people living with SMA. The impact on the incidence and prevalence on milder types of SMA is still unclear and difficult to predict due to a more variable life expectancy. This growing population is already influencing the demand for specialist neuromuscular services to provide effective assessment, care and advice as per the standards of care. It has risen noticeably for both paediatric and adult population and it's likely to continue to do so in the upcoming years. Currently SMA REACH has a registered population of over 800 individuals, of which 2/3 are paediatric patients. Whilst the SMA population is increasing, there is anecdotal evidence that service provision and capacity have remained the same. Additionally, the experience from the Adult SMAREACH network has proved the developing nature of many of the recruited sites trying to meet demands of the service. In the UK, since the introduction of DMT under the Managed Access Agreement (MAA) on 2019 to date, no evidence has been published about the potential impact that this has had on the overall population. We aim to describe the evolution in population figures in the UK due to the potential impact of survival rate in different disease severity groups. Data from 2019 up to 2024 will be collected via the national neuromuscular database (NND) by SMA Type, for both paediatric and adult networks and describe trends over time. Additionally, describing the cohort characteristics: SMN2 copy number, sex, and current characteristics of age, time on DMT, type of DMT, scoliosis, spinal surgery, respiratory status, current function (WHO motor milestone).