CardioExchange Archive

Although the general benefits of lowering high blood pressure are widely accepted, there has been intense debate over specific goals for treatment and the threshold at which therapy should be initiated.  A large new meta-analsysis published in JAMA helps shed lights on this important controversy.

U.K. and Australian researchers analyzed the effect of lowering blood pressure in type 2 diabetes using data from more than 100,000 people who participated in 40 trials. They found that lowering blood pressure was beneficial: for each 10-mm Hg drop in systolic blood pressure, there were statistically significant reductions in mortality, cardiovascular events, coronary heart disease, stroke, albuminuria, and retinopathy. For instance, each 10-mm Hg drop was associated with a 13% reduction in mortality and a 27% reduction in stroke — translating into absolute risk reductions of 3.16 and 4.06 events per 1,000 patient-years, respectively.

However, when the trials were stratified according to whether systolic blood pressure at baseline was above or below 140 mm Hg, relative risks for outcomes other than stroke, retinopathy, and albuminuria were lower for those with initial blood pressures of 140 or higher. Similarly, when the trials were compared according to the blood pressure levels reached during the trial, relative risks for most outcomes were lower in patients achieving a systolic blood pressure of 130 mm Hg or higher versus those reaching lower levels, with the exception of stroke and albuminuria.

The authors take issue with the recent JNC 8 guideline which raised the threshold for treatment in diabetics to 140 mm Hg. They recommend that therapy should be considered at the lower level in people at high risk for stroke, retinopathy, and progression of albuminuria.

In an accompanying editorial, Bryan Williams writes that the findings “are timely, clear, and important and lend support to current guideline recommendations to consider offering patients with type 2 diabetes antihypertensive therapy when their systolic BP is 140 mm Hg or greater, aiming for a target systolic BP toward 130 mm Hg but not usually lower than this.” But, he continues, “for some patients, these treatment thresholds and targets might be too conservative, especially for optimally reducing the risk of stroke and the development or progression of albuminuria.”