Smoking, heart rate, and ischemic stroke: a population-based prospective cohort study among Inner Mongolians in China.

BACKGROUND AND PURPOSE Smoking is a major public health challenge and an important risk factor for cardiovascular diseases. No previous studies have evaluated the association among smoking, heart rate, and ischemic stroke in an Inner Mongolian population. We aim to evaluate the cumulative effect of smoking and heart rate on ischemic stroke incidence in this population. METHODS A prospective cohort study from June 2003 through July 2012 was conducted among 2530 people ≥20 years of age from Inner Mongolia, China. We categorized the participants into 4 subgroups according to smoking status and heart rate. Cox proportional hazards models and receiver operating characteristic curves were used to evaluate the association among smoking, heart rate, and ischemic stroke. RESULTS The multivariate-adjusted hazard ratios (95% confidence intervals) of ischemic stroke incidence for nonsmokers with heart rate ≥80 bpm, smokers with heart rate <80 bpm, and smokers with heart rate ≥80 bpm were 1.42 (0.62-3.28), 2.11 (1.06-4.23), and 2.86 (1.33-6.14), respectively, compared with nonsmokers with heart rate <80 bpm. The area under receiver operating characteristic curve (area under the curve) for a model containing smoking status and heart rate, along with conventional factors (area under the curve=0.755), was significantly (P=0.018) larger than the one containing only conventional factors (area under the curve=0.739). CONCLUSIONS Our study indicated that smoking was an independent risk factor of ischemic stroke, and smokers with faster heart rate had the highest risk of ischemic stroke among Inner Mongolians. These findings suggest that smoking status and heart rate may be valuable in predicting ischemic stroke incidence.