Global Prevalence and Epidemiology

Multiple Sclerosis Worldwide

The epidemiology of multiple sclerosis (MS) is well studied owing to its prevalence and position as the main cause of non-traumatic disability among young adults. The usual age of onset for relapsing-remitting MS (RRMS) is 20-35, while primary progressive MS (PPMS) is usually diagnosed around the age of 40. In a significant proportion (up to 10%) of patients with MS, the first demyelinating event occurs before the age of 18.

According to an analysis of data from the Global Burden of Disease (GBD) 2016 Study, there were an estimated 2.2 million prevalent cases of MS worldwide in 2016, up 10.4% in age-standardized prevalence since 1990. The highest prevalence rates (per 100,000 people) were observed in high income North America (164.6), western Europe (127.0) and Australasia (91.1), while the lowest rates were recorded in eastern sub-Saharan Africa (3.3), central sub-Saharan Africa (2.8) and Oceania (2.0). Prevalence of MS increases as a function of age, markedly increasing after the age of 25. It also diverges for men and women after puberty, with approximately a 2:1 ratio in adult women and men. Furthermore, while prevalence seems to each a plateau in both sexes by the age of 60, in women there is another increase after the age of 80, which is not observed in men.

An analysis of the Global Burden of Disease 2019 Study found that, in 2019, there were 59,345 incident cases of MS (up from 41,854 in 1990) and 22,439 MS-associated deaths (up from 13,356 in 1990) globally in 2019. However, the age-standardized rate (ASR) of incidence per 100,000 people has decreased slightly (from 0.8 in 1990 to 0.7 in 2019) and remained stable for deaths (0.3 in 1990 and 2019). Disability-adjusted life years (DALYs), a measure of the number of healthy years of life lost to MS-associated disability or death, increased in absolute numbers from 726,066 in 1990 to 1,159,832 in 2019, but declined in ASR (16.1 in 1990 compared to 14.0 in 2019). A comparison of ASRs for incidence, death and DALYs is shown in Figure 1-2. As this figure shows, high-income North America, Europe and Australasia had higher ASR compared to other regions.

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Based on an analysis of private, military, Medicaid and Medicare health claims data sets, there were a total of 744,781 cases of MS in the United States in the years 2008-2010, of which 76% were in women and 24% in men. Most cases (77%) were in White individuals, with 10% in Black individuals, 7% in Hispanic individuals and 4% in individuals classified as “non-Hispanic other”. The rates per 100,000 people were highest for White people (374.8), followed by Black people (298.4), people in “the non-Hispanic other” category (197.7) and Hispanic people (161.2). The overall female to male ratio was 2.9:1. With respect to age, the highest prevalence was in the 45-64 age category. The map of the contiguous United States shown in Figure 1-3 shows the prevalence of MS, by state, from 2008 to 2010.

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