Blood pressure medications not equal, researchers say
WINSTON-SALEM, N.C. - A blood pressure medicine's success at lowering pressure shouldn't be the only measure of its effectiveness, say researchers from Wake Forest University Baptist Medical Center and colleagues in an editorial in this week's Annals of Internal Medicine. "We all agree that high blood pressure should be lowered. New scientific evidence strongly suggests that it matters how we do it," said Curt Furberg, M.D., Ph.D., professor of public health sciences at Wake Forest.
"We tend to forget that drugs have multiple actions that may add to or subtract from the benefit of blood pressure lowering itself. Some drugs, for example, reduce the risks of heart attack and heart failure through other mechanisms. Therefore, which drug is used to control high blood pressure may be very important."
In their editorial, the authors argue that drugs that are equally effective at lowering pressure may vary widely in how well they prevent complications of high blood pressure - heart attacks, strokes and heart failure. They called for better ways of evaluating and testing hypertension drugs. "We point out that the intended use of hypertension drugs is to reduce the complications of high blood pressure, not just to lower pressure," said Furberg. "Adopting this view would require a change in the way these drugs are approved and promoted."
To prove their point that a drug's effectiveness shouldn't be measured by blood pressure-lowering alone, the authors gave examples of several recent studies.
· Part of the ALLHAT (Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack) study was stopped early when participants taking doxazosin (sold under the name Cardura®) had 25 percent more serious complications (heart failure and strokes) from hypertension than the group taking the much less expensive diuretic chlorthalidone. The participants in the Cardura group were twice as likely to develop or be hospitalized for heart failure.
· An analysis of four studies comparing blood pressure drugs found that ACE (angiotensin converting enzyme) inhibitors are more effective than other drugs in reducing the risk for heart attacks, but not stroke, in patients with diabetes.
· An analysis of nine studies comparing long-acting calcium channel blockers with other hypertension drugs found that the agents were equally effective at lowering pressure, but that calcium channel blockers were associated with 25 percent higher rates of heart attacks and heart failure.
"We've behaved as if blood pressure lowering drugs have only one effect," said Furberg. "These studies remind us that this is a simplistic view. Prevention of cardiovascular complications is likely to be affected by the way in which blood pressure is lowered." The authors said new types of hypertension drugs should be compared head-to-head with the standard therapy, which is currently a low-dose diuretic. Rather than measuring how well the drugs lower pressure, the studies should compare their effectiveness at preventing heart attacks, strokes and congestive heart failure, the authors said.
"Treatment decisions should be based on the results from properly-designed research trials," said Furberg. "Relying on data about blood pressure-lowering alone may not be in the patients' best interest."
Co-authors were Bruce M. Psaty, M.D., Ph.D., from the University of Washington, Seattle; Marco Pahor, M.D., Wake Forest University Baptist Medical Center; and Michael H. Alderman, M.D., Albert Einstein College of Medicine, Bronx, N.Y.