Systolic Blood Pressure Levels Among Adults With Hypertension and Incident Cardiovascular Events: The Atherosclerosis Risk in Communities Study
Is the risk for cardiovascular (CV) events low when adults with hypertension (HTN) have lower systolic blood pressure (SBP)?
Participants in the ARIC (Atherosclerosis Risk in Communities) study, who had a diagnosis of HTN but no known CV disease (CVD) at baseline (1987-89), were included in the present analysis. Measurements of SBP were taken at baseline and at three triennial visits. SBP was grouped into three categories (140 mm Hg or higher; 120-139 mm Hg; and a reference level of lower than 120 mm Hg). Multivariable Cox regression models included baseline age, sex, diabetes status, body mass index, high cholesterol level, smoking status, and alcohol intake. The primary outcome of interest was composite CVD events including heart failure, ischemic stroke, myocardial infarction, or death related to coronary heart disease.
A total of 4,480 adults were included and followed over a median of 21.8 years. A total of 1,622 incident CVD events occurred during follow-up. Of the ARIC participants with HTN, 43.7% had elevated SBP (≥140 mm Hg), 33.6% had standard SBP (120-139 mm Hg), and 22.7% had low SBP (<120 mm Hg). Participants in the elevated SBP category tended to be older, were more likely to be male and African American, and were somewhat more likely to have diabetes. There was a high prevalence of being overweight, and almost three-quarters were taking antihypertensive medication. Almost one-fifth of the cohort had diabetes, and two-thirds of the cohort had some smoking or alcohol history. Participants with elevated SBP developed incident CV events at a significantly higher rate than those in the low BP group (adjusted hazard ratio [HR], 1.46; 95% confidence interval [CI], 1.26-1.69). However, there was no difference in incident CV event-free survival among those in the standard versus low SBP group (adjusted HR, 1.00; 95% CI, 0.85-1.17). Further adjustment for BP medication use or diastolic BP did not significantly affect the results.
The investigators concluded that among patients with HTN, having an elevated SBP carries increased risk for CV events, but in this categorical analysis, once SBP was below 140 mm Hg, an SBP lower than 120 mm Hg did not appear to lessen the risk of incident CV events.
These data from a large cohort of biracial adults suggest no added benefit in CVD risk reduction when SBP is lowered beyond 140 mm Hg. Risk reduction was observed for higher levels of SBP. These data support recommendations for adequate therapy to reduce SBP to <140 mm Hg. However, further research is warranted to understand whether <150 mm Hg for a SPB goal is preferable for some patients.
Keywords: Myocardial Infarction, Stroke, Follow-Up Studies, Atherosclerosis, Overweight, Risk Reduction Behavior, Disease-Free Survival, Smoking, Cholesterol, Body Mass Index, Heart Failure, Confidence Intervals, Hypertension, Diabetes Mellitus
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