Drug for High Blood Pressure Cuts Stroke 36%
The use of a standard hypertension drug to treat a kind of high blood pressure that afflicts mainly older Americans caused a dramatic reduction in the incidence of stroke, heart attack and other types of cardiovascular disease among a study group, federal researchers reported Tuesday.
The study has major public health implications for the estimated 3 million to 4 million Americans older than 60 who suffer from isolated systolic hypertension.
The study’s results showed that low doses of a frequently prescribed diuretic, chlorthalidone, combined in some cases with a low dose of a beta blocker, atenolol, decreased stroke by 36%, heart attack by 27% and all cardiovascular disease by 32%.
Before the study was designed, there was some question about whether anti-hypertensive drugs would be effective in treating those with isolated systolic high blood pressure, said Dr. William McFate Smith, clinical professor of medicine at UC San Francisco and one of the study investigators. In fact, many clinicians resisted using the therapy in this age group because they feared that the drugs might actually induce strokes or could produce harmful side effects, such as fainting, that could cause a serious fall, he said.
“The . . . results disprove one myth about old age: that stroke is an inevitable consequence of aging,” said Dr. T. Franklin Williams, director of the National Institute on Aging, which sponsored the study with the National Heart, Lung and Blood Institute. “We . . . health care providers must offer this treatment to our older patients as quickly as possible.”
Federal health officials estimated that treatment using the two drugs, which costs less than 25 cents a day, could prevent about 75,000 strokes and heart attacks every year in the elderly population and could save an estimated $500 million a year in hospital and other related costs for treating them.
The study was published in today’s issue of the Journal of the American Medical Assn.
An estimated 50 million to 60 million Americans suffer from high blood pressure, a known major risk factor for stroke--the No. 3 killer of Americans--and heart disease, the leading cause of death in this country.
Blood pressure readings are typically given in two numbers, such as 120/80. The first number represents the systolic pressure, which is the force produced in the artery each time the blood is pushed from the heart into the large blood vessels. The second number, known as the diastolic pressure, is the pressure that exists in the arteries when the heart is relaxing between beats.
The average normal blood pressure reading for adults is 120/80. In older people, many experts believe that readings up to 140/90 are acceptable. Once the blood pressure goes above this level, however, some form of treatment may be required.
Isolated systolic hypertension means that the pumping pressure of the heart as it pushes blood into the arteries is higher than it should be. The systolic component of blood pressure usually rises throughout life, while the diastolic levels out in the middle to late 50s and declines slightly thereafter.
Isolated systolic hypertension is associated with a two to three times higher risk of stroke, as well as an increased risk of coronary heart disease, heart failure, heart attack and sudden death from cardiovascular disease.
The number of older individuals suffering from this type of high blood pressure is expected to increase to 8 million to 10 million by the year 2025, the heart institute said. The condition hits older black women the hardest; they have twice the rate of isolated systolic hypertension as white women and black or white men.
Smith said that previous studies had shown the value of anti-hypertensive drugs in treating diastolic hypertension--the more common kind--but that this study had demonstrated for the first time that the therapy also would work in the type of hypertension that most frequently strikes the elderly.
In 1980, a small three-year pilot study involving 551 subjects was launched as a first step to answer these questions, Smith said.
The full-scale study began in 1984 at 16 clinical centers across the nation. The study involved 4,736 participants whose average age was 72. Their systolic pressure was between 160 and 220, and their diastolic pressure was less than 90.
Participants were assigned either to receive the drug alone, the drug in combination with the beta blocker--a category of drugs that regulates the heartbeat--or a medically worthless placebo.
Most of those in the placebo group remained on it throughout the study, although some ultimately were given the drugs if they suffered from “prolonged markedly high blood pressure,” said Dr. Jeffrey L. Probstfield of the heart institute, who served as the study’s project director.
After five years, the incidence of stroke was 5.2 for every 100 patients for those on the therapy, contrasted with 8.2 for every 100 for the placebo group, Probstfield said. Put another way, there were 30 fewer episodes of stroke per 1,000 participants taking the drugs over the five-year study, he said.
“This represents a 36% reduction, which is highly significant statistically,” he said.
Similarly, researchers saw a 27% reduction in heart attacks among those taking the drugs, finding 16 fewer heart attacks per 1,000 participants taking the drugs over the five-year period, Probstfield said.
Finally, there was a 32% overall reduction in all cardiovascular disease among those taking the drugs, including strokes, heart attacks and heart failure, he said.
Moreover, the drugs--which were given at lower than standard doses--produced no side effects, researchers said.
Study participants took half the standard dose of chlorthalidone--12.5 milligrams a day. It usually is prescribed at 25 milligrams daily for routine treatment of high blood pressure.
The drugs, both made by Stuart Pharmaceuticals, are already on the market. Researchers predicted that other diuretics and beta blockers, which are also available, would be likely to show the same results as those used in the study.
Fighting Disease: Signs of Progress
Daily, low-dosage use of two drugs resulted in a dramatic drop in the number of strokes, heart attacks and other cardiovascular diseases suffered by a group of older Americans, a federal study found. The five-year study reported that use of chlorthalidone and atenolol resulted in:
* A 36% reduction in strokes
* A 27% reduction in heart attacks
* A 32% reduction in all cardiovascular diseases (including strokes and heart attacks).
