Stroke in the people’s republic of China: I. geographic variations in incidence and risk factors

Background and Purpose Stroke is a major cause of death in the People's Republic of China (PRC), and the geographic distribution of stroke death varies substantially. We conducted an ecological analysis to investigate the relationship of prevalence of hypertension and other risk factors with stroke incidence and mortality in the PRC. MethodsThe relationship between prevalence of risk factors and stroke incidence and mortality in the PRC was assessed in 29 provinces by examining risk factor data from PRC national surveys and incidence and mortality from the 1986 PRC National Stroke Study. Results A highly statistically significant correlation between prevalence of hypertension and stroke incidence (r equals .838, P less than .001) and mortality (r equals .841, P less than .001) was observed. Prevalence of hypertension explained over 70% of the geographic variability in stroke incidence (partial R² equals .703) and mortality (partial R² equals .707) in the PRC. There was a north-south gradient, with a higher prevalence of hypertension and stroke incidence and mortality in the north compared with the south of the country. In multiple Poisson regression analysis, a 10% increase in the prevalence of hypertension was associated with a 2.80-fold higher incidence and 2.68-fold higher mortality from stroke, whereas a 10% increase in the prevalence of alcohol consumption was associated with a 29% higher incidence and a 16% higher mortality from stroke. A 10% increase in the prevalence of cigarette smoking was associated with a 19% higher mortality from stroke. Conclusions In the PRC, the prevalence of hypertension is strongly associated with the risk of stroke, and the geographic variation in stroke incidence and mortality is due mainly to differences in the prevalence of hypertension.