Blood pressure: How low to go?

Sept. 11, 2015 -- When it comes to treating high blood pressure, lower is better, a new study shows.

The study, which was stopped early on Friday because the results were so clear and positive for one group of patients, found that getting high blood pressure back down to normal levels -- at least 120/80 -- dramatically cuts the risk of heart attacks, strokes, and deaths compared to currently recommended BP targets.

“Monday morning, this will be all we talk about,” says Mary Norine Walsh, MD, a cardiologist and vice president of the American College of Cardiology.

"This can have a very large effect on thousands and thousands of people. One in three people in the United States have hypertension, and the majority of those people are over the age of 50," says Walsh, who was not involved in the research.

The results are contrary to current clinical guidelines. New blood pressure targets released last year advised doctors to loosen treatment targets for patients with high blood pressure. Most patients over age 60, for example, were advised to shoot for a goal of 150/90.

“The trend, I think, in the thinking of the community of physicians who treat high blood pressure has really been more towards higher goals,” says David Reboussin, PhD, professor of public health sciences at Wake Forest Baptist Medical Center in Winston-Salem, N.C. Reboussin was part of a team of doctors who led the study for the National Institutes of Health.

"But most of those opinions were formed really without the benefit of a definitive, large clinical trial to test the hypothesis of whether it is better or not. That's what we set out to do," Reboussin says.

The study had enrolled more than 9,000 adults over the age of 50. All of them had high blood pressure. And they all had at least one additional heart risk factor, like a history of heart disease.

Study participants were randomly assigned to two groups. Doctors treated patients in the first group to get their systolic blood pressure to a goal of 140. The goal for the second group was to get their systolic blood pressure back to normal -- anything under 120.

Both groups were told to follow a low-sodium diet and to exercise, and doctors could use any combination of medications needed to meet those targets. On average, the participants needed three different medications to get to a goal of 120, compared to two medications in the group that aimed for a goal of 140.

The results were striking. Patients in the lower blood pressure group had roughly a third fewer heart attacks, strokes, and diagnoses of heart failure compared to patients that had the slightly higher blood pressure target goal. The lower group also had about 25% fewer deaths.

WebMD asked Reboussin and another doctor involved in the study, George Thomas, MD, director of the Center for Blood Pressure Disorders at the Cleveland Clinic, what these results mean for people with high BP.

Q: People are going to hear this news today and wonder what they should do about it. What’s your advice?

Reboussin: They should continue taking their current blood pressure medications. No one is in any immediate danger unless they make changes on their own without talking to their doctor. Stay on your current medications. Talk to your doctor. We will be releasing information as soon as we can complete the analyses to help doctors and patients make informed decisions about what's best for each individual patient's care.

Q: Can you tell whether it mattered how people got to those goals as far as what drugs they were on?

Reboussin: We haven't found any special effect of a particular medication or a particular dose. It seems to really be something you can attribute to the fact that the blood pressure itself is lower.

Q: How unusual is it for the government to stop a study early this way?

Thomas: That happens only when there are really significant results.

All studies are monitored by a data-safety monitoring board. And if they feel there’s a study that’s clearly positive or clearly negative, then ethically, they have to recommend stopping the study so the information can be sent out to the public as soon as possible.

Q: There’s been some debate in medicine about the ideal numbers for people with high blood pressure.

Thomas: Yes. Normal blood pressure is defined as the systolic -- the upper number -- being less than 120 and the diastolic -- the lower number -- being less than 80.

But in patients who have a diagnosis of hypertension and are on treatment, we've always asked the question, "How low should you go?'"

Should we lower blood pressure to normal levels of less than 120/80? There was no clear evidence from any of the large studies to answer that question. This is really the first large, well-designed study to show that more-intensive control is better. So that’s pretty significant.

Q: Before the study, what did you tell your patients?

Thomas: Regular practice is to keep them less than 140.

The most recent guidelines, because they didn’t have any other evidence, they also endorsed the target of a systolic pressure of less than 140. So that’s what most of us have been doing. We don’t necessarily try to be more aggressive than that.

Q: It’s pretty hard, isn’t it, just to get patients under 140?

Thomas: It is hard. I want to see more data. We know there's benefit, but at what cost? Are there any adverse effects in the intensive group? Did they have more falls with injuries? [Sudden blood pressure dips can cause dizziness and make people more likely to fall.] Did they have a higher occurrence of kidney failure [from taking more medication]? They're still analyzing that part. That will give us a little more clarity on how to manage our patients. Some patients may not tolerate getting to that lower level.

Q: Will this study change how doctors treat patients?

Thomas: Yes. But there are two sides to this.

This is an important study. It is a landmark study. The results cannot be questioned because it was large, it was pretty well-designed. It was a randomized trial, and randomized trials are essentially the gold standard for clinical research. So I don’t think anyone can question the benefits.

The other side to this is for an individual patient, how can we apply it in clinical practice? In my mind, individual decisions will have to be made. We can try to reach a target of 120, but it will all depend on how patients tolerate taking the extra medication.

Reboussin: At this point, it's mostly been the investigators that were part of the study that have been looking at the results, and we really need the benefit of wisdom in the broader community before we can put them in context.

I think the study will change how doctors practice, but you want to be careful, if you’re someone who is taking blood pressure medications, not to make any immediate changes. Stay on your current medications. Talk to your doctor about what to do next. For our part, we’re going to try to make that information available to the medical community as quickly as we can.

SOURCES:Mary Norine Walsh, MD, medical director of heart failure and transplantation, St. Vincent Medical Group in Indianapolis, Ind.; vice president, American College of Cardiology.David Reboussin, PhD, professor of public health sciences, Wake Forest Baptist Medical Center, Winston-Salem, N.C.George Thomas, MD, director, Center for Blood Pressure Disorders, Cleveland Clinic, Cleveland, Ohio.News release, National Heart, Lung and Blood Institute.