Register for Low-dose aspirin is best choice for cutting bleeding risks
AnginaOctober 15, 2003
A little aspirin goes a long way in helping to prevent heart attacks and strokes while reducing bleeding complications, according to a new study.
The new findings emerged from a large international clinical trial called Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE). The study tested a combination of two antiplatelet agents that help prevent blood clots: aspirin and clopidogrel. CURE participants had unstable angina.
Blood clots are a major cause of heart attacks and strokes.
The main goal of the trial was to test the effectiveness of clopidogrel and aspirin vs. aspirin alone. CURE researchers reported last year that patients in the combination arm suffered significantly fewer severe cardiovascular problems than the aspirin-only group - 9.3% compared with 11.4%.
However, the study also provided an opportunity to assess the safety and efficacy of various aspirin doses, with or without clopidogrel.
"Experimentally, a single 100 mg dose of aspirin is sufficient in healthy individuals to inhibit platelet aggregation," said lead author Ron J.G. Peters, MD, of the Academic Medical Center in Amsterdam, the Netherlands.
The researchers suggested that the optimal daily aspirin dose for reducing acute coronary syndromes (ACS) may be between 75 and 100 mg. ACS is a general term for heart attack or angina.
Peters said the findings from CURE could lead to a significant change in the aspirin dose recommended for ACS patients.
CURE researchers said their new analysis demonstrates three important points:
1) The benefits of clopidogrel do not vary significantly with the dose of aspirin used.
2) Higher aspirin doses are not associated with a lower rate of cardiovascular events, "and may, in fact, be associated with higher event rates."
3) Higher doses of aspirin increase the risk of major bleeding events, whether aspirin is taken alone or with clopidogrel.
The CURE study compared the daily use of aspirin alone with aspirin plus clopidogrel in 12,562 ACS patients. All patients were prescribed aspirin, with the dose determined by the participating medical institution, and the patients were randomized to receive clopidogrel or a placebo for up to a year after admission.
The CURE protocol recommended a daily aspirin dose between 75 mg and 325 mg. In the present analysis, aspirin use was divided into three groups; less than or equal to 100 mg, 101 through 199 mg, and 200 mg or greater. Among the study participants, 5320 received a low dose of aspirin, 3109 took the medium dose, and 4110 got a high dose.
Peters noted that there is no uniformity in the aspirin doses used in clinical practice.
Within each participating institution, aspirin dosage didn't vary significantly, but across geographic regions the range was much larger, he said. The highest dose was most common in Canada and the United States, while researchers in Latin America were the second most likely to use a high-dose aspirin regimen. The medium doses were used in Australia and New Zealand, and the lowest doses were used in Eastern and Western Europe.
Among the clopidogrel-treated patients, the amount of aspirin taken daily did not significantly affect the rate at which they suffered a cardiovascular death, heart attack or stroke. Nor was there a significant difference in these outcomes among the three aspirin doses in the aspirin-only group.
Conversely, "major bleeding complications increased significantly with increasing aspirin dose, both in the placebo and the clopidogrel group," Peters said. "The bleeding rate was in fact slightly lower for low-dose aspirin plus clopidogrel than for high-dose aspirin alone."
In the placebo group, the bleeding risk was 1.9% with low-dose aspirin, 2.8% with medium-dose aspirin, and 3.7% with high aspirin doses. Bleeding risks for the clopidogrel patients were 3.0% on low-dose aspirin, 3.4% on medium-dose, and 4.9% on high-dose.
Peters said lowering the dose of aspirin may substantially lessen the risk of major bleeding.
"This type of evidence will certainly be very important in the development of our revised guidelines for aspirin use," said Sidney C. Smith, MD, former chief science officer and a national spokesperson for the American Heart Association. This article was prepared by Health & Medicine Week editors from staff and other reports.
©Copyright 2003, via NewsRx.com & NewsRx.net
