A huge scientific study has found that aspirin alone is just as effective as aspirin and the anti-clotting drug warfarin in preventing death, second heart attacks and stroke. The study involved 5,050 men and women at 78 different sites, and lasted more than six years. Researchers lowered the aspirin dose to 81 milligrams — versus 162 milligrams when taking the drug alone — and the warfarin dose to between 1.5 and 2.5 International Units — the standard dose is 2.5 to 3.5 International Units.
"We used a lower intensity than recommended when using warfarin alone because we thought putting them together would cause too much bleeding," Fiore explains. "In retrospect, we now think that was the mistake, that you need to use both drugs at full dose. If we did it again, we would leave aspirin at 81 milligrams and use the standard dose of warfarin."
All of the 5,050 participants had suffered a heart attack within 14 days of enrolling in the study. Each was followed for a median of 2.7 years.
When all was said and done, there were no appreciable differences between the two groups. In the segment of patients receiving the combined therapy, 17.6 percent died, compared with 17.3 percent in the aspirin-only group. In the combination group, 13.3 percent had a second heart attack versus 13.1 percent in the aspirin group. A small number — 3.5 percent — of patients receiving both drugs had a stroke, while a slightly smaller number — 3.1 percent — of aspirin-only participants suffered a stroke.
People in the combination group had nearly twice as many major bleeding episodes as the aspirin group. The bleeding, however, stayed within acceptable levels in both groups, Fiore says.
"It would have been nice if it had positive results because, at low dosages, it was a very safe combination," Fiore says. "We tried for a home run with big efficacy and low toxicity, but it was a long shot."
Fiore’s initial study proposal had called for a higher dose of warfarin, but the reviewing committee refused to approve it. Source: Circulation 02-2002