January 23, 2018
Blood Pressure: How Low to Go
Be Well

Blood Pressure: How Low to Go

by John Swartzberg, M.D.  

If you have high blood pressure (hyperten­sion) and take medication to reduce it, are you and your doctor aiming low enough? You may be wondering about that if you heard about the widely publicized findings of a large government-sponsored study in November 2015. Several readers have asked me about it. The current recommendation is to lower blood pressure to below 140/90 (or below 150/90 for most people ages 60 and older). But the new study, published in the New England Journal of Medicine, strongly suggests that reduc­ing systolic blood pressure (the first number) well under that level—to below 120—could significantly reduce cardiovascular disease and premature deaths in many people with hypertension.

Called SPRINT (Systolic Blood Pressure Intervention Trial), the study included more than 9,300 subjects over age 50 with hyperten­sion and at least one other cardiovascular risk factor (but not diabetes or a history of stroke). Half the subjects took medication to aim for a systolic target below 140; the other half were assigned a more aggres­sive target of below 120. The study was halted early, after an average of three years, when it became clear that the lower target was having substantial benefits—a 25 percent reduced risk of cardiovascular events (primarily heart failure and deaths) compared to the standard target. One additional cardiovascular event was prevented in every 61 people in the 120-target group during the three-year period.

The findings don’t constitute a formal recommendation, which is expected to come from updated professional guidelines. But while a lower target may sound like a good idea, I think it’s too soon for most people to aim so low.

For one thing, it’s often challenging to achieve the lower goal. In the study, people aiming for systolic pressure of below 120 had to take three drugs, on average, compared to two drugs in the 140-target group. As part of a clinical trial, they received top-notch and frequent medical supervision, including adjustment of medications, which not everyone can get in the real world, where about half of all people treated for hypertension don’t even get their systolic pressure down to 140.

Another concern: Even with careful monitoring, about twice as many of the 120-target participants experienced some well-known side effects of intensive treatment—such as fainting, electrolyte abnormalities, and reversible kidney damage—compared to the 140-target group.

The researchers are continuing to analyze the data and follow the SPRINT participants to better assess the effects—good and bad—of aggressive treatment. For instance, will people aiming for 120 have additional benefits, such as a reduced risk of cognitive decline, dementia, and chronic kidney disease?

There are some key questions that SPRINT can’t answer because of the study’s design. Notably, will people with diabetes, those under 50, and others at lower cardiovascular risk (all excluded from SPRINT) also benefit enough from the lower target?

There is no one-size-fits-all treatment and target for people with hypertension. If you are being treated for the disorder and are at ele­vated cardiovascular risk, like the SPRINT participants, talk to your doc­tor about the potential benefits and risks of a lower treatment goal. The best option, of course, would be to lower your blood pressure fur­ther by making lifestyle changes, such as losing excess weight, quit­ting smoking, exercising, moderating your alcohol intake, and improving your diet (things your doctor probably encouraged from day one). SPRINT didn’t test those measures, which have additional benefits besides those coming from lower blood pressure.