Incidence and prevalence of multiple sclerosis in China and other Asian countries.

The prevalence of multiple sclerosis (MS) in Asian countries is thought to be lower than in Western countries, with Asian populations presenting 80% less risk of MS than white populations. Incidence and prevalence rates in Asian countries are therefore not well defined and their association with rates in neighboring countries, as well as with ethnic, environmental, and socioeconomic factors, are not well understood. We performed a comprehensive literature review of epidemiological data from China and neighbouring countries to study the frequency of the disease, focusing on prevalence, and the progression over time and the influence of sex-related, environmental, dietary, and sociocultural factors. Prevalence rates in China range between 0.88 cases/100,000 population in 1986 and 5.2 cases/100,000 population in 2013, with a non-significant upwards trend (p = .08). The increase observed in Japan, where figures ranged between 8.1 and 18.6 cases/100,000 population was highly significant (p < .001). Prevalence rates in countries with predominantly white populations are considerably higher and have increased over time, reaching 115 cases/100,000 population in 2015 (r = 0.79, p < .0001). In conclusion, the prevalence of MS in China appears to have risen in recent years, although Asian populations (including Chinese and Japanese populations, among others) appear to present less risk than other populations. Within Asia, geographical latitude appears not to be a determining factor for developing MS.