TUESDAY, May 8, 2007 (HealthDay News) -- A daily aspirin dose of 75 to 81 milligrams is best for the long-term prevention of cardiovascular disease and stroke without causing serious side effects, a new study found.
Higher doses of aspirin, which are commonly prescribed, don't offer better protection and are associated with increased risks of gastrointestinal bleeding, the study authors said.
"We wanted to find out whether there was strong evidence favoring higher or lower doses of aspirin," said lead author Dr. Charles L. Campbell, an assistant professor of medicine at the University of Kentucky. "Because recommendations vary, clinicians don't know what to do."
More than 50 million adults in the United States take aspirin regularly for long-term prevention against heart attack and stroke. Typically, doses are either 81 milligrams a day or 325 milligrams a day. The appropriate long-term daily dose remains a matter of contention.
To try to discover which dose is best, Campbell's team reviewed 11 clinical trials. Based on that review, the researchers found that aspirin doses as low as 30 milligrams a day are effective in inhibiting clot-causing platelets from accumulating, although doses as high as 1,300 milligrams a day are approved for use.
In the United States, 81 milligrams a day of aspirin is the most commonly prescribed dose, accounting for 60 percent of prescriptions. It's followed by 325 milligrams a day, accounting for 35 percent of all prescriptions, according to the report.
"We could find no evidence that a higher dose of aspirin provided more efficacy than lower doses of aspirin," Campbell said." On the contrary, every trend is to see more bleeding on higher doses."
The results are published in the May 9 issue of the Journal of the American Medical Association.
Campbell recommends that people at risk for a first or second heart attack take no more than 81 milligrams of aspirin a day. "People should evaluate their need for aspirin with their physician," he said. "But they shouldn't take any more than an 81 milligram chewable or baby aspirin a day."
Dr. Jeffrey S. Berger, a cardiology fellow at Duke University Medical Center, said the study seems to suggest that lower doses of aspirin are best for preventing cardiovascular disease, but more evidence is needed for the finding to be conclusive.
"There is really not a lot of data for using a higher dose of aspirin," he said. "But the study also shows that there really isn't enough data to adequately compare lower versus higher dose."
Berger added that people who have had a heart attack or stroke and are taking aspirin should be on the lowest dose. "As of right now, it seems as if there is no benefit with a higher dose," he said. "And there is data to suggest that higher doses are associated with worse outcomes."
More information
For more on aspirin's heart-protecting powers, visit the American Heart Association.
