Incidence and risks of subarachnoid hemorrhage in China.

BACKGROUND AND PURPOSE To determine incidence and risks of subarachnoid hemorrhage in China. METHODS A prospective, population-based, 1:2 matched case-control study in Baotou, Inner Mongolia (≈2 million population) in 2009-2011. Multiple variable models used to determine relative risk and population-attributable risks for exposures. RESULTS For a total of 226 patients (mean age, 59 years; 65% women; 434 controls), crude annual incidence (per 100 000) of subarachnoid hemorrhage was 6.2 (95% confidence intervals, 5.4-7.0); 4.3 (3.3-5.2) for men and 8.2 (6.9-9.6) for women. Compared with nonsmokers, adjusted relative risk of subarachnoid hemorrhage in current smokers was 2.31 (95% confidence interval, 1.31-4.09) but was 4.00 (1.62-9.89) in women. Population-attributable risk for smoking, hypertension, and low income were 18%, 36% and 59%, respectively. CONCLUSIONS The incidence of subarachnoid hemorrhage in China is slightly lower than in Western countries and is related to smoking, hypertension, and poor socioeconomic status.