Anti-clot drug combinations boost bleeding risks

CHICAGO (Reuters) - Heart patients are often given two or three different drugs to prevent life-threatening blood clots but these combinations can double, triple or even quadruple the risk of stomach or intestinal bleeding, U.S. researchers said on Tuesday.

Clot-preventing drugs such as aspirin, warfarin or Coumadin and clopidogrel or Plavix sold by Bristol-Myers Squibb and Sanofi-Aventis are increasingly being given to heart patients in combinations.

"They are often prescribed to prevent that second event -- that heart attack or stroke," Dr. Neena Abraham of Baylor College of Medicine in Houston, Texas, told reporters at the Digestive Disease Week meeting in Chicago.

"However, each of these drugs independently is associated with a high risk of clinically significant upper gastrointestinal events, which are defined as ulcers of the stomach or intestines, bleeding or perforations," she said.

"These drugs are commonly prescribed in combination; however, the magnitude of the risk of using these drugs on the gastrointestinal tract remains relatively unknown."

To study this, Abraham and colleagues used national pharmacy data and medical records from the Veterans Affairs Department to identify people aged 60 to 99 who had been given four combinations of clot-preventing drugs.

Some got aspirin and an antiplatelet drug like Plavix that keeps blood platelets from forming clots. Others got an antiplatelet drug and an anticoagulant such as warfarin, which keeps the liver from making certain clotting factors. Some got aspirin and warfarin. And some got all three.

Of the more than 78,000 patients studied, 30.4 percent were prescribed some combination of anticlotting drugs, and 1,061 of these had bleeding events that needed immediate medical attention within the first year.

RISING RISK

"When we compared the risk of bleeding from these different combinations, what we see is a stepwise increase in risk," Abraham said.

The dual combination of an anticoagulant and antiplatelet drug, which proved to be least harmful, raised the risk of a serious bleeding problem within one year by 70 percent.

A combination of an aspirin and antiplatelet drug doubled the risk, while an aspirin-anticoagulant combination tripled the one-year bleeding risk.

And patients who got all three drugs had a four-fold increase in the risk of gastrointestinal bleeding within one year, Abraham said.

"These are significant gastrointestinal bleeding risks."

Abraham said triple therapy was most commonly given to younger patients in the study -- those aged 60 and 69 years of age -- and likely reflected recent changes in cardiac care.

She said the findings suggest the need for a careful balancing of the risks and benefits of these drugs.

Heart patients on triple therapy may want to ask their doctor about dropping down to a dual or single therapy.

"We know they are healthy for the heart at preventing strokes and heart attacks, but what physicians now need to consider is short-term potential risks of GI bleeding versus the potential long-term benefits of being on these protective drugs," she said.

(Editing by Vicki Allen)