March 4 (UPI) -- People may want to think twice about using aspirin to prevent heart attacks or stroke, a study says.
Nearly 6 percent of patients taking both aspirin and the stroke prevention drug warfarin had major bleeding episodes within a year of beginning the treatment, according to a study published Monday in JAMA Internal Medicine. That's compared to 3.3 percent of people who only took warfarin.
Patients taking the combination also visited the hospital and emergency room to treat excessive bleeding more often.
"Nearly 2,500 patients who were prescribed warfarin were taking aspirin without any clear reason, over a seven-year period," Geoffrey Barnes, a vascular cardiologist at the University of Michigan and study senior author, said in a news release. "No doctors really own the prescribing of aspirin, so it's possible it got overlooked."
This led researchers to conclude that one-third of them should either start taking drugs to suppress bleeding in their stomachs or stop using one of the blood thinners.
"Clinicians should ask their patients who are anticoagulated with warfarin if they're taking aspirin as well," said first author Jordan Schaefer, a hematologist at Michigan Medicine and assistant professor of internal medicine. "For the patients who are on both therapies, clinicians should review their medical history to determine if it's really necessary to be on both drugs."
Other studies have shown that taking aspirin can cut cardiovascular risk by 11 percent, but also acknowledge that major bleeding is a side effect.
Now, the researchers want to reach out to anticoagulation clinics that target people using the combination to see whether the therapy is actually necessary.
"There's been some hint of this being an issue for a long time," Schaefer says. "Now based on these new findings, we're working to reduce the number of patients on aspirin without a clear reason for both drugs."