At what systolic blood pressure should we begin treatment for the most benefit?
Beginning antihypertensive treatment when the systolic blood pressure is greater than 140 mm Hg delays death and prevents major cardiovascular events in some persons without preexisting heart disease; in patients with existing heart disease, it prevents further events, but does not extend life. These results may appear to conflict with those from the Systolic Blood Pressure Intervention Trial (SPRINT), which found benefit with lowering systolic blood pressure to below 120 mm Hg. However, the SPRINT investigators measured blood pressure using automated devices, which give readings 10 to 20 mm Hg lower than typical office measurements. The goal of less than 120 mm Hg in the SPRINT study is likely to be very similar to the goal of less than 140 mm Hg in this study. (Level of Evidence = 1a)
The authors followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to search three databases, including Cochrane Central, as well as reference lists of identified studies to identify all randomized trials with at least 1,000 patient-years of follow-up that compared drug treatment with placebo or compared blood pressure targets against one another. Two researchers independently extracted the data and assessed the quality of the research (more than two-thirds of the studies had a low risk of bias). They identified 74 studies enrolling 306,273 patients (60.1% men, average age = 63.6 years).
In patients without preexisting heart disease (i.e., primary prevention), lowering systolic blood pressure that was initially greater than 140 mm Hg decreased the risk of death (relative risk [RR] = 0.93; 95% confidence interval [CI], −0.88 to 1.0 if systolic blood pressure is greater than 160 mm Hg; RR = 0.87; 95% CI, 0.75 to 1.0 if systolic blood pressure is 140 to 159 mm Hg) and major cardiovascular events (RR = 0.78; 95% CI, 0.7 to 0.87 if systolic blood pressure is greater than 160 mm Hg; RR = 0.88; 95% CI, 0.8 to 0.96 if systolic blood pressure is 140 to 159 mm Hg). Treating systolic blood pressure that was initially less than 140 mm Hg did not affect morbidity or mortality. In patients with previous coronary heart disease and a mean systolic blood pressure of 138 mm Hg, treatment reduced the risk of further major cardiovascular events (RR = 0.9; 95% CI, 0.84 to 0.97), but did not extend life. There was a high degree of heterogeneity among these trial results, reducing our confidence in the results. There was some evidence of publication bias in the studies that evaluated the effect on major cardiovascular events, meaning that the studies failing to show a difference in outcomes were not published.
Study design: Meta-analysis (randomized controlled trials)
Funding source: Foundation
Setting: Various (meta-analysis)
Reference:BrunströmMCarlbergBAssociation of blood pressure lowering with mortality and cardiovascular disease across blood pressure levels: a systematic review and meta-analysis. JAMA Intern Med2018;178(1):28–36.