TRENTON, N.J. -- Diuretics, pills used by millions of elderly 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 with 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 the pills because research linked them to diabetes.
The new study, published in this month's 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 UMDNJ-Robert Wood Johnson Medical School in New Brunswick, N.J.
Kostis and colleagues at the University of Texas School of Public Health in Houston tracked 4,732 patients with high blood pressure who had been in a federal study in the 1980s that proved diuretics sharply reduced the risk of heart failure, heart attack, and stroke. Half of those patients had been given chlorthalidone, from the most common class of diuretics.
After an average of 14.3 years, 19 percent of the patients who had been in the diuretics group were dead from cardiovascular causes, compared with 22 percent from the dummy pill group.
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 the patients who developed diabetes, there was a 32 percent lower risk of cardiovascular death in the diuretics group.
Dr. Valentin Fuster, a 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.
The study will further increase the use of diuretics, which work by increasing the production of urine, Fuster said.
Used in conjunction with dietary measures to reduce salt consumption and increase potassium, diuretics are medicine's oldest blood pressure drug. They cost just pennies a day, while some of the newest, most complex blood pressure drugs can cost up to 50 times more.
''Diuretics are not supported by the [drug] industry because they're cheap and generic," Kostis said.
Dr. Richard Milani, vice chairman of cardiology at Ochsner Clinic in New Orleans, said that for patients who can't afford pricey new blood pressure drugs like angiotension receptor blockers, ''this is going to allow for these people to be treated [with diuretics] with less guilt."
Milani said the newer classes of blood pressure drugs don't lead to diabetes and may reduce the risk of developing it, so he prefers them.