Smoking, Hypertension, and Their Combined Effect on Ischemic Stroke Incidence: A Prospective Study among Inner Mongolians in China.

OBJECTIVE: We intended to investigate the combined effect of smoking and hypertension on ischemic stroke incidence based on a 10-year prospective study among Inner Mongolians in China. METHODS: A prospective cohort study from June 2003 to July 2012 was conducted among 2589 participants aged 20 years and older from Inner Mongolia, China. We categorized the participants into 4 subgroups according to the status of smoking and hypertension. The cumulative incidence rates of ischemic stroke among the 4 subgroups were estimated using Kaplan-Meier curves and compared by log-rank test. Cox proportional hazard model was used to compute hazard ratios of ischemic stroke across the 4 subgroups after adjusting for important confounding factors. RESULTS: The cumulative incidence rates of ischemic stroke were .85%, 2.05%, 3.19%, and 8.14% among non-hypertension/non-smokers, non-hypertension/smokers, hypertension/non-smokers, and hypertension/smokers, respectively. The multivariable-adjusted hazard ratios [95% confidence intervals] of ischemic stroke for hypertension and smoking were 1.84 [1.05-3.23] and 1.89 [1.11-3.22], respectively. The hazard ratios [95% confidence intervals] of ischemic stroke for non-hypertension/smokers, hypertension/non-smokers, and hypertension/smokers were 1.37 [.56-3.33], 1.34 [.54-3.29], and 2.93 [1.26-6.83], respectively, compared with the non-hypertension/non-smokers. Significant interaction was detected between smoking and hypertension on the risk of ischemic stroke. CONCLUSIONS: Our study indicated that participants with coexistence of smoking and hypertension were at the highest risk for ischemic stroke. There was a significant interaction between smoking and hypertension on the risk of ischemic stroke.

Prehypertension and cardiovascular risk factor clustering among Mongolian population in rural and animal husbandry area, Inner Mongolia, China.

BACKGROUND: It is unclear whether and to what extent there is clustering of cardiovascular risk factors in the prehypertension phase among Mongolians in the rural and animal husbandry area of Inner Mongolia, China. METHODS AND RESULTS: The 2,589 Mongolian people aged > or=20 years served as subjects. Demographic data, lifestyle factors and family history of hypertension, blood pressure measurements, physical examination and blood samples were obtained and analyzed for all individuals. The proportions of 2 and > or =3 risk factors clustering were higher in hypertensives than in prehypertensives, and higher in prehypertensives than in normotensives (both P<0.01). After adjustment for age, sex and family history of hypertension, both prehypertension and hypertension were associated with mutually clustering of 5 risk factors; odds ratio (OR) of prehypertension with 1, 2 and > or =3 factors was 1.30 (1.02, 1.65), 1.93 (1.40, 2.67) and 2.44 (1.62, 3.68), respectively, and for hypertension the OR were 1.75 (1.31, 2.35), 3.84 (2.68, 5.48) and 6.95 (5.04, 10.63), respectively. CONCLUSIONS: There is clustering of risk factors in the phase of prehypertension among Mongolian people, so intervention measures should be taken to prevent progression to hypertension and other cardiovascular diseases.

Combined effects of family history of CVD and heart rate on ischemic stroke incidence among Inner Mongolians in China.

OBJECTIVE: This study aimed to evaluate the combined effects of family history of cardiovascular diseases (FHCVD) and heart rate on ischemic stroke incidence among Inner Mongolians in China. METHODS: A prospective cohort study was conducted among 2589 participants aged 20 years and older from Inner Mongolia, China. The participants were divided into four groups according to status of FHCVD and heart rate and followed up from June 2002 to July 2012. Cox proportional hazards models were used to evaluate the combined effects of FHCVD and heart rate on the incidence of ischemic stroke. RESULTS: A total of 76 ischemic stroke occurred during the follow-up period. The observed ischemic stroke cases tended to be older and male, and had higher prevalence of smoking, drinking, hypertension and FHCVD as well as higher systolic and diastolic blood pressures at baseline compared with those who did not experience ischemic stroke. Age- and gender-adjusted hazard ratio (95% confidence interval) of ischemic stroke in the participants with both FHCVD and heart rate ≥ 80 were 2.89 (1.51-5.53), compared with those without FHCVD and heart rate < 80. After multiple adjustment, the association between ischemic stroke risk and both FHCVD and heart rate ≥ 80 remained statistically significant (hazard ratio, 2.47; 95% confidence interval: 1.22-5.01). DISCUSSION: Our main finding that participants with both FHCVD and faster heart rate have the highest risk of ischemic stroke suggests that faster heart rate may increase the risk of ischemic stroke among people with FHCVD.

Clustering of cardiovascular risk factors and stroke: a prospective cohort study in Inner Mongolia.

OBJECTIVE: This study aimed to evaluate the effect of clustering of cardiovascular risk factors (CVRF) on stroke incidence and find some high predictive clusters among Inner Mongolians in China. METHODS: A prospective cohort study was conducted among 2589 participants aged 20 and older from Inner Mongolia, China. The participants were divided into four groups according to the number of CVRFs and followed up from June 2002 to July 2012. Cox proportional hazards model was used to evaluate the clustering of CVRFs on the incidence of stroke. Area under curve was used to compare the effect of every cluster on stroke and find those having higher predictive value. RESULTS: A total of 124 stroke occurred during the follow-up period. The incident stroke cases tended to be older and male; had higher prevalence of smoking, drinking, and family history of cardiovascular diseases (FHCVD); had greater waist circumference, higher systolic and diastolic blood pressure, and C-reactive protein levels at baseline compared with those who did not experience stroke. Unadjusted hazard ratio (HR) (95% confidence interval) of stroke in the participants with at least three CVRFs was 5.230 (2.646-10.336), compared with those without CVRF. After multiple adjustments, the result remained statistically significant (HR, 3.388; 95% confidence interval: 1.678-6.840). On the basis of FHCVD, clustering of hypertension with other CVRFs and clustering of diabetes with tachycardia had higher predictive value than other clustering. CONCLUSION: The clustering of CVRFs increased the risk of stroke. On the basis of FHCVD, the clustering of hypertension with other CVRFs and the clustering of diabetes with tachycardia had higher predictive value for stroke than other cluster.