Prevalence of multiple system atrophy: A literature review

• The majority of MSA epidemiological studies were mainly conducted in Europe and few were conducted in Brazil, Japan and the USA. • MSA prevalence studies were mainly prospective population-based studies or multi-center studies. • The estimated crude prevalence of MSA ranged from 0.52–17/100,000 persons and was higher among men than women (2.75 vs. 1.19 per 100,000 persons) • Age-specific prevalence rates varied and increased with age. • The variation in MSA prevalence could be attributed to differences in demographics, study methodology, diagnostic criteria, and case assessment strategies of MSA. This paper aims to provide a literature overview on multiple system atrophy (MSA) prevalence in European and other pan-European populations. A literature search (PubMed, EMBASE) was performed through 2022 to identify published studies on MSA prevalence in European countries. Of these search results, titles and abstracts were screened for relevance. A standardized assessment tool was used for systematically data extraction and comparison. For studies where only the incidence rate was reported, MSA prevalence was derived based on the incidence and duration of disease. A total of 24 studies conducted in 14 countries and published between 1995 and 2022 were identified. The prevalence of MSA was reported in 18 (75%) studies and was derived from six (25%) incidence studies. These studies were mainly prospective population-based studies or multi-center studies from specific regions or specialty clinical settings. Two earlier studies in Germany and the Netherlands were conducted using door-to-door design. The time period of evaluation of prevalence ranged from 1990 to 2018. The crude prevalence of MSA ranged from 0.5/100,000 in Spain to 17/100,000 in Japan. Age-specific prevalence rates were provided in five studies, and the reported age ranges varied. The gender-specific crude prevalence was estimated as 2.75/100,000 for men and 1.19/100.000 for women. The derived prevalence was higher (ranging from 0.7–18.9/100,000) than studies where the prevalence was reported. The variations observed in MSA prevalence may result from differences in age distributions of the study populations, study methodology, diagnostic criteria and case assessment strategies of MSA. Thus, the comparability of these studies is limited.