On-treatment Blood Pressure And Stroke In Essential Hypertensive Patients With Low-moderate Vascular Risk

Background: China is of high morbidity of stroke and relatively lower morbidity of heart diseases. Blood pressure(BP) is the most important preventable risk factor for stroke and other cardiovascular(CV) diseases. Then are BP levels the lower the better? It was still in dispute. Our aim was to investigate which BP levels are best to prevent stroke in Chinese hypertensive patients with low-moderate cardiovascular risk.Methods: This was a post-hoc analysis of the China Stroke Primary Prevention Trial, which was a multicenter, double-blind randomized trial. It compared the outcome effects of enalapril maleate and folic acid tablets with that of enalapril maleate in 20702 essential hypertensives aged 45 to 75 years and without a history of stroke, myocardial infarction and heart failure. Average on-treatment BP was calculated for each patient using mean of all but their baseline BP measurements until stroke or death occurred. The follow-up was given every 3 months for 4.5 years. Patients were categorized into five groups by their average on-treatment systolic BP(≥150 mm Hg, 140 to <150 mm Hg, 130 to <140 mm Hg, 120 to <130 mm Hg and <120 mm Hg) and into five groups by average diastolic BP(≥90 mm Hg, 85 to <90 mm Hg, 80 to <85 mm Hg, 75 to <80 mm Hg and <75 mm Hg). The rate of total stroke and its types were compared among BP groups using Kaplan-Meier plots and Cox proportional hazard regression model with BP groups of 130-140/ 80-85 mm Hg as the reference respectively. Subgroup analysis was performed by stratifying the cohort with the CV risk factors at baseline, including age, sex, center and history of diabetes or chronic kidney disease.Results: A total of 637 stroke events(3.1%) occurred in the 20702 essential hypertensive patients. A J-shaped relationship between BP and total stroke was found in the smooth curve with a nadir of 123.8/ 78.9 mm Hg. In comparing with the systolic BP of 130 to <140 mm Hg group, the risk of stroke was significantly higher in the 140 to <150 mm Hg group(adjusted HR, 1.63;95% CI,1.30-2.04;P<0.001); was significantly lower in the 120 to <130 mm Hg group(adjusted HR, 0.64;95% CI,0.44-0.93;P=0.018); and then significantly higher in the <120 mm Hg(adjusted HR, 2.13;95% CI,1.12-4.07;P=0.022). In comparing with the diastolic BP of 80 to <85 mm Hg group, there was a significant increase of total stroke in the 85 to <90 mm Hg group(adjusted HR, 1.67; 95% CI, 1.32-2.12; P<0.001); and a significant reduction in the 75 to <80 mm Hg group(adjusted HR, 0.64; 95% CI, 0.49-0.85; P=0.002). The results were consistent for younger and elderly, male and female, patients lived in the northern and southern areas, and patients with and without diabetes or chronic kidney disease.Conclusions: To prevent stroke in essential hypertensive patients with low-moderate cardiovascular risk in China, the optimal goal of systolic BP is 120 to <130 mm Hg, and 75 to <80 mm Hg for diastolic BP. A systolic BP goal of 130 to <140 mm Hg is recommended for patients aged ≥60 years and those with diabetes or chronic kidney disease.