Low-Dose Aspirin Reduces Cardiovascular Events
DURHAM, N.C. -- Taking low-dose aspirin daily reduces the
risk of heart attack and stroke, as well as the risk of dying,
among patients who previously have had a heart attack or stroke
but whose cardiovascular disease has stabilized, according to a
new analysis by Duke University Medical Center
The study also found that taking low-dose aspirin daily
increases a patient's risk of bleeding, but the researchers
said the protective benefits of aspirin outweigh this side
effect. A daily dose of aspirin is considered low if it is
between 81 milligrams and 325 milligrams.
"Among patients with stable cardiovascular disease, we found
that low-dose aspirin reduced incidence of heart attack, stroke
and death," said cardiology fellow Jeffrey Berger, M.D., who
presented the results of the study on Wednesday, Nov. 15, at
the annual scientific sessions of the American Heart
Association, in Chicago.
"We also saw an increased risk of bleeding among patients
taking aspirin, but as in the decision-making process involving
any therapy, there is always the weighing of benefits and
risks," Berger added. "Since a great majority of patients can
tolerate aspirin, the benefits appear to outweigh the risks.
Aspirin is a drug that has been used for many years. It is
well-understood, effective, inexpensive and widely available.
In aspirin we have a proven life-saver."
The study was supported by Duke's Division of
Aspirin exerts its protective effect by preventing the
clumping together of platelets circulating in the blood,
according to the researchers. It is this anticlotting action
that also causes unwanted bleeding.
In the Duke study, Berger and colleagues combined the data
from six clinical trials that enrolled patients with stable
cardiovascular disease or stable angina, or chest pain, and
gave them low-dose aspirin. In total, the trials included 9,853
The researchers found that patients who took low-dose
aspirin had a 26 percent reduction in the risk of a nonfatal
heart attack, a 25 percent reduction in the risk of stroke and
a 13 percent reduction in risk of death, compared with similar
heart patients who did not take aspirin. Taken together, Berger
said, patients on low-dose aspirin had a 21 percent reduction
in risk of experiencing a major cardiovascular event, a
measurement that is the combination of the rates of nonfatal
heart attack and stroke and of cardiovascular death.
In terms of aspirin's effect in promoting bleeding, the
study found that one patient out of 111 who received low-dose
aspirin experienced a bleeding episode, Berger said.
Putting the results another way, Berger said, the results
suggest that treating 83 patients will prevent one nonfatal
heart attack, treating 40 patients will prevent one stroke,
treating 30 patients will prevent one major cardiovascular
event and treating 71 patients will prevent one death.
"When compared to other medications that have been proven
effective in preventing cardiovascular events, aspirin comes
off looking very good," Berger said.
For example, 91 patients would need to be treated with ACE
inhibitors to prevent one death, compared with 71 patients for
aspirin, he said. ACE inhibitors dilate blood vessels, making
it easier for the heart to pump blood. Ninety-one patients
would need to be treated with the inhibitors to prevent one
heart attack, compared with 83 for aspirin, and 167 would need
to be treated with the inhibitors to prevent one stroke,
compared with 40 patients with aspirin.
"These comparisons show that a cheap and inexpensive
medicine like aspirin is just as good, if not better, than
other expensive medicines," Berger said.
Still, there is room for improvement in aspirin therapy, he
said. In particular, he said, more study is needed to identify
what dosage in the low-dose range -- from 81 milligrams to 325
milligrams a day -- will provide the best benefit-to-risk
Other members of the research team were Richard Becker of
Duke and David Brown of the State University of New York-Stony
Brook Medical Center.