In the thought provoking paper by Xu et. al., the authors conducted a systematic review of studies looking at the incidences of stroke in China in order to establish if and where there is a “stroke belt” in China. Prevalence of stroke risk factors in these provinces was extrapolated from nationwide epidemiological surveys. The “stroke belt” is defined as provinces ranked in the top third for stroke incidence in the nation with at least one third of their prefectural regions ranked in the top two sevenths of prefectural regions for stroke incidence. Nine provinces met criteria for the “stroke belt”. The incidence of stroke within the belt was more than twice of other regions. It appears that there is a noticeable north-south gradient with provinces that met the criteria in northern and western China. Hypertension and BMI > 25 correlated with higher stroke incidences in those provinces.
It is interesting to note that most of the studies the authors included analyzing the incidences of stroke in China were from the 1980s. As the world knows, the staggering pace of Chinese economic growth is rapidly changing the population distribution in China. One challenge to future stroke epidemiological studies in China is its growing “flowing population”, as people move from the country side to the city, from underdeveloped economic areas to developed ones, and from central and western regions to coastal regions. It will be important for future studies to account for this dynamic variable as well as the increasing westernization of diet and living habits and deleterious environmental changes in the face of globalization.