Raising Systolic BP Target May Hike Stroke Risk

Pauline Anderson

February 12, 2015

NASHVILLE, TENNESSEE — Older patients without diabetes or kidney disease who have a systolic blood pressure (SBP) of 140 to 149 mm Hg have a risk for stroke higher than that of similar patients with a SBP under 140 mm Hg and a risk similar to that of patients with a level of 150 mm Hg and over, a new study shows.

This is particularly true for African American and Hispanic patients, the researchers found.

In light of these findings, recent new recommendations to increase target SBP from 140 to 150 mm Hg in older patients could have a detrimental effect on stroke risk, especially among minority populations, according to study authors.

The research was presented here at the International Stroke Conference (ISC) 2015.

Last year, the Eighth Joint National Committee (JNC 8) recommended increasing the current SBP target of 140 mm Hg to 150 mm Hg in patients aged 60 and older without diabetes mellitus or chronic kidney disease. The recommendations were published February 5, 2014, in JAMA.

Researchers for the current study aimed to find out whether raising this threshold would have a harmful effect, explained lead author Ralph Sacco, MD, Department of Neurology, University of Miami, Florida.

Dr Ralph Sacco

"We wanted to look at what impact this would have in our study on stroke because there is lot of evidence that hypertension is one of the most important risk factors for stroke," Dr Sacco said.

The study included 1706 patients over 60 years of age who had not had a stroke and did not have chronic kidney disease or diabetes. These patients were part of the Northern Manhattan Study (NOMAS), a prospective longitudinal study started in 1993.

The mean age of this cohort was 72 years; 37% of patients were male. About a quarter were white, another quarter were non-Hispanic black, and almost 50% were Hispanic. About 41% were receiving antihypertensive medication.

In the 1706 patients, SBP was less than 140 mm Hg in 43%, 140 to 149 mm Hg in 20%, and 150 mm Hg or greater in 37%.

Over a median of 13 years of follow-up, there were 167 strokes, most of which (86%) were ischemic.

After adjustment for age, sex, race-ethnicity, and BP medication use, researchers found that compared to those with SBP less than 140 mm Hg, the hazard ratio (HR) for stroke among those with SBP of 140 to 149 mm Hg was 1.7 (95% confidence interval [CI], 1.2 - 2.6).

Among those with the highest SBP (>150 mm Hg), the HR was 1.4 (95% CI, 0.9 - 2.0; proportionality test: P = .17).

"Just as Deleterious"

"We found that the group with 140 to 149 was just as deleterious as 150 and above; so if you have a systolic blood pressure of 140 to 149 it's probably just as bad as having it over 150," Dr Sacco told a press conference here.

The results showed that the increased risk was seen in Hispanics and non-Hispanic blacks but not in non-Hispanic whites.

In older patients, said Dr Sacco, raising the threshold "will actually lead to a few more strokes in our society." This, he added, raises doubts about the appropriateness of increasing the recommended SBP threshold in these patients.

Session moderator, Jose Biller, MD, professor, neurology, and medical director, Stroke Program, Loyola University, Maywood, Illinois, said he also takes exception to the JNC 8 recommendation to raise the SBP target.

"I do not believe the available data were sufficient for such a recommendation," he told Medscape Medical News. "The epidemiological study presented by Dr Sacco corroborates those concerns."

Potential Bias

Studies such as this one would not have met inclusion criteria for studies assessed by the JNC 8 panel because of quality concerns related to potential bias, said Paul James, MD, professor and chair, Department of Family Medicine, University of Iowa, one of two cochairs of the JNC 8 panel.

"The panel discussed studies with similar findings and with the exception of a minority of members, we were not persuaded because of inadequate randomized controlled trial evidence to support the lower BP goals," he told Medscape Medical News.

The challenge, said Dr James, is that patients with lower blood pressure at the start of a study have less severe hypertension and a lower risk for stroke. "So analyses based on lower BPs are not reliable in observational cohorts to make recommendations on goal BPs." 

Controversial Recommendations

The JNC 8 recommendations have been controversial. There was even division among the committee members drafting them, said Dr Sacco. He pointed out that several panel members wrote a minority report disagreeing with the decision to change the SBP threshold level in this group of patients, published in April 2014 in the Annals of Internal Medicine.

"They didn't take into account the totality of the evidence," Dr Sacco said of the panel's decision. "Every single other study has shown such strong relationships — linear, positive, strong relationships between raising blood pressure and particularly stroke risk. Also, there was nobody on the panel that was a stroke neurologist — there was one hypertension expert — but stroke was not looked at as seriously as a vascular neurologist would like to look at it."

According to Raj Padwal, MD, cochair, Canadian Hypertension Education Program (CHEP), and associate professor, medicine, University of Alberta, Canada, critics maintain that the JNC took "a narrow view" of the available literature. "It excluded studies that encompassed millions of patients."

And while the panel might argue that the gold standard for making treatment recommendations requires randomized controlled trials, it also excluded relevant randomized controlled trials, said Dr Padwal.

"Even among the randomized controlled trial evidence, they only looked at a selected part of the published data," Dr Padwal pointed out.

Dr Sacco said the panel put particular weight on one clinical trial in an Asian population that was older and had different levels of blood pressure control.

Nothing "Earth Shattering"

While this new study is yet another example of why people are a "little bit nervous" about raising the SBP threshold, "it's nothing earth-shatteringly new," said Dr Padwal. "It just reinforces what we have known from many, many previous studies: that the threshold for an increase in complications does occur and in fact, occurs all the way down to a blood pressure of around 110."

As far as Dr Padwal is aware, only a minority of groups approve of the proposed increase, and most clinicians are still using the JNC 7 recommendation of 140 mm Hg as a SBP threshold for hypertension.

"Although certain organizations, for example, some family medicine groups, have endorsed JNC 8 and have said they are going to go to 150, the vast majority of institutions and organizations and practitioners have said 'no, we don't accept this, it's too narrow a view of the evidence, and we're just going to use JNC 7'."

The American Heart Association (AHA) is preparing additional guidance on this issue, Dr Sacco noted. Current AHA President Elliott Antman, MD, Brigham and Women's Hospital, Boston, Massachusetts, announced at the meeting here that the AHA is developing additional hypertension statements, he said.

The study was supported by the National Institute of Neurological Disorders and Stroke. Dr Sacco has disclosed no relevant financial relationships.

International Stroke Conference (ISC) 2015. Abstract 79. Presented February 11, 2015.


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