Diuretics, pills used by millions of people to lower high blood pressure, clearly reduce the long-term risk of death from heart attacks and strokes, according to a study that could ease fears that the medication's risks outweigh its benefits.
Diuretics, which work by removing fluid from the body, have been used for decades. But doctors have realized in the past few years that the drugs raise the risk of developing diabetes, which itself can lead to heart attacks and strokes.
As a result, some doctors were afraid that diuretics' risks would cancel out their benefits.
The first long-term study to examine the question found that while diuretics do raise the risk of diabetes, the rate of death from heart attacks or strokes was still nearly 15 percent lower in patients getting a diuretic compared to those who were given dummy pills.
"This is the most conclusive information we're likely to have, at least for some time," said Dr. Jeffrey Cutler, senior scientific adviser at the National Heart, Lung and Blood Institute, a sponsor of the study. "I think this will further reassure physicians."
National guidelines list diuretics as a first-line treatment for high blood pressure. Nevertheless, some doctors have avoided prescribing diuretics since research linked them to diabetes.
The new study, published in the January issue of the American Journal of Cardiology, was partly funded by the National Institute on Aging and the Robert Wood Johnson Foundation of Plainsboro, N.J. It was led by Dr. John Kostis, director of the Cardiovascular Institute at the University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School in New Brunswick, N.J.
The researchers looked at chlorthalidone, a member of the most common class of diuretics.
Kostis and colleagues at the University of Texas School of Public Health in Houston followed 4,732 patients with high blood pressure for an average of more than 14 years. At the end of that period, 19 percent of patients given diuretics were dead from cardiovascular causes, compared with 22 percent of those who got dummy pills.
When the study began, about 17 percent of patients in each group had diabetes. During the four years that followed, an additional 13 percent of patients on diuretics and 9 percent of patients on dummy pills developed diabetes.
Among patients who developed diabetes, there was a 32 percent lower risk of cardiovascular death in the diuretics group.
Dr. Valentin Fuster, former American Heart Association president and director of the Cardiovascular Institute at Mount Sinai School of Medicine in New York, said the study answers a critical question for doctors because about one-third of people over 60 have both high blood pressure and diabetes.
Diuretics, medicine's oldest blood pressure drug, cost pennies a day. Some of the newest, most complex blood pressure drugs can cost up to 50 times more.