Estimating the prevalence and incidence of multiple system atrophy in the USA: Insights from a national claims database

Published literature on the prevalence and incidence of multiple system atrophy (MSA) in the US are scarce or based on relatively older studies. The objective of this study was to estimate the prevalence and cumulative incidence of MSA in the US.This was a retrospective study of individuals aged 30 years or older in a large US claims database from 2016 to 2021. The primary endpoint was ≥1 MSA claim. Persons with ≥2 MSA claims were also examined. Incident cases aged ≥30 years with a minimum of one-year of continuous enrollment prior to and following cohort entry were identified. Prevalence and cumulative incidence of MSA were estimated for year 2021 and were also standardized to the 2021 US population.The crude prevalence of MSA was 7.2 per 100,000 persons in 2021 and increased with age. After standardization to the US population, the age-adjusted prevalence was 12.4 per 100,000 translating to 41,133 persons in the 2021 US population. In persons with ≥2 MSA claims, the crude and age-adjusted prevalence were 3.1 and 5.7 per 100,000 persons. The crude cumulative incidence of MSA for individuals aged 30 years and older was 9.8 per 100,000 persons in 2021. The estimated cumulative incidence of MSA in individuals 30 years or older, age-adjusted to the 2021 U S. population, was 14.2 per 100,000.This study provides real-world evidence on the prevalence and cumulative incidence of MSA in the US to better understand the medical care needs and treatment.