UF study reveals black patients require more medicines at higher doses to control blood pressure

May 16, 2003

GAINESVILLE, Fla. — Cardiologists have long acknowledged that high blood pressure is more difficult to treat in patients of certain racial or ethnic origins. That’s especially true for black people, who are at higher risk of developing the condition, are often afflicted with it at a younger age and are less likely to respond to medications designed to control it.

Now University of Florida researchers who spearheaded a landmark hypertension study have found that many blacks actually can lower their blood pressure to levels similar to those achieved by their white counterparts – but they have to take more medicines at higher doses to do it. The scientists also discovered that contrary to popular belief, blacks were not more likely to experience complications associated with heart disease and high blood pressure, such as heart attack, stroke or death.

The findings, reported today [5/16] at the American Society of Hypertension’s annual meeting in New York, also reveal new information about Hispanics – who achieved blood pressure-lowering goals better than whites or blacks and were largely spared adverse effects – and come on the heels of an announcement Wednesday by the National Heart, Lung and Blood Institute recommending new blood pressure guidelines. According to the institute’s findings, anything below 120/80 would be considered normal, and readings between 120/80 and 140/90 would be considered prehypertensive.

The UF results came out of two years of follow-up data gleaned from more than 22,000 patients with coronary artery disease and high blood pressure who participated in the International Verapamil SR-Trandolapril study, funded by Abbott Laboratories and known as INVEST. The trial was the first coronary artery disease study to adequately represent women and minorities, UF researchers said. More than half the participants were women, and the study included more than 8,000 Hispanics and 3,000 blacks.

“Some studies have suggested that hypertension is much more likely to lead to adverse outcomes such as death, stroke or heart attack in black individuals compared with non-blacks, but we didn’t see that in INVEST,” said Dr. Carl J. Pepine, chief of cardiovascular medicine at UF’s College of Medicine and the INVEST study’s principal investigator. “But in order to achieve equivalent outcomes, blacks used higher doses and more drugs than whites. So the message is it’s not realistic to think about single drugs. It’s more likely that these patients will require two, three or more drugs to manage their blood pressure or higher doses to manage their blood pressure in order to achieve these good outcomes.”

Why Hispanics in particular were spared some of the devastating consequences of hypertension and coronary artery disease is not yet clear, said Rhonda Cooper-DeHoff, a research assistant professor at UF’s College of Medicine and assistant director of the division of cardiovascular medicine’s clinical trials program. On average, the incidence of adverse events in the Hispanic population was 20 percent to 30 percent lower than in blacks or whites.

“Up to now there’s been very little information in the medical literature on Hispanics and blood pressure reduction,” Cooper-DeHoff said. “INVEST is one of the first two studies to look at blood pressure reduction in Hispanics with documented heart disease.”

The INVEST study was designed to settle the long-standing debate over the usefulness of calcium antagonists for treating high blood pressure. In April, researchers announced the drugs are part of a safe and effective regimen for patients who don’t respond to standard medicines – or who stop taking them because of bothersome side effects.

In the current analysis, researchers did not account for which drugs participants took, calcium antagonists or the traditional medicines, beta-blockers. That analysis will be conducted later, Cooper-DeHoff said, along with other analyses intended to discern whether specific genetic factors influence how blacks, whites and Hispanics metabolize drugs and respond to them, or contribute to the incidence of heart attack, stroke or death in patients with high blood pressure and heart disease. Someday patients might walk into their doctor’s office with a card detailing their genetic make-up, and treatment could be tailored accordingly, she added.

“A doctor could put that card into a computer and determine which drugs a patient should take for a condition like high blood pressure based on their genetic make-up,” she said. “We’re a long way from that for all kinds of reasons, but that’s certainly the goal.”

More than 50 million Americans have high blood pressure, according to the American Heart Association. In addition, elevated blood pressure is associated with up to half of the estimated 15,000 cases of coronary artery disease. In recent years, doctors have reassessed the ideal blood pressure targets.

In the INVEST study, UF researchers tracked participants for two to five years to determine whether a high blood pressure treatment strategy that included a sustained-release form of the nondihydropyridine calcium antagonist verapamil was at least as effective as beta-blockers and diuretics at lowering blood pressure below 140/90. Patients at 862 sites around the world were randomly assigned to one of the two strategies.

Calcium antagonists decrease the work of the heart’s blood pumping, reduce the pressure of blood flow through the body and improve blood circulation through heart muscle. Since the 1960s, beta-blockers have ranked among the most widely used drugs for the treatment of high blood pressure. The drugs fight the condition by reducing the heart’s workload, slowing heart rate and decreasing the force with which the heart muscle contracts. Diuretics lower blood pressure.

Those assigned to the verapamil strategy also could receive the angiotensin-converting enzyme, or ACE, inhibitor trandolapril and/or a diuretic to achieve the target blood pressure or minimize side effects. Those in the study’s other arm also could use trandolapril if needed. (ACE inhibitors block an enzyme in the body that causes blood vessels to narrow. If blood vessels are relaxed, blood pressure decreases, and the heart uses less oxygen to pump blood.)

Researchers found that both approaches controlled high blood pressure exceptionally well, lowering it below 140/90 in more than 72 percent of study participants, who were mostly elderly. In addition, the calcium antagonist strategy was just as effective at preventing adverse outcomes such as heart attack, stroke or death during the study as the traditional approach.