Combined Effects of Hypertension and Heart Rate on the Risk of Incident Stroke Among Mongolian, China

Objective: Stroke is a major public health challenge in China. Hypertension is an important risk factor for stroke, and heart rate may play an important role in stroke development. This study prospectively investigated the joint effects of hypertension and heart rate on the risk of stroke incidence among Mongolian, China. Design and method: A cohort study of 2589 Mongolian people were conducted from 2002 to 2012 in 32 villages in Tong Liao City of Inner Mongolia, China. Baseline data were collected, and blood pressure, body weight, height, heart rate, and waist circumference were measured, the participants were followed up and study outcome was defined as incident stroke during following up. According to the hypertensive status and heart rate, the participants were divided into following groups: normotensives/low heart rate, normotensives/high heart rate, hypertensives/low heart rate, and hypertensives/high heart rate. Hazard ratios (HRs) and 95% confidence intervals (CIs) for incident stroke were calculated by Cox proportional hazard models. The discriminatory value of hypertension/heart rate on stroke was assessed by computing the area under receiver operating characteristic curves. Results: During the 9.2 years of follow-up, a total of 124 stroke patients occurred, the cumulative incidence rate was 4.79%. After multivariable adjustment, compared with the normotensives with low heart rate, the HRs (95% CI) of incident stroke were 3.19(1.80-5.66) for hypertensives with low heart rate, 1.77 (0.84-3.74) for normotensives with high heart rate and 3.84 (1.95-6.24) for hypertensives with high heart rate, respectively. The AUC for the model including hypertension and high heart rate and other conventional risk factors was larger than that for the model including only other conventional risk factors (0.854 vs 0.836, P=0.023). Conclusions: This study showed that hypertensives with high heart rate had the highest risk of stroke among inner Mongolians in China. Our findings suggested that the coexistence of hypertension and high heart rate may be a valuable predictor of stroke incidence.