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THURSDAY, Aug. 5 (HealthDayNews) -- Transfusions of platelets during coronary artery bypass surgery seem to boost the risk of death as well as infection and stroke.

To arrive at this conclusion, researchers from Virginia Commonwealth University Medical Center and other institutions evaluated data from six clinical trials at 37 medical centers in the United States, Denmark and Israel from 1990 to 1995. The trials were conducted to evaluate aprotinin, a drug used to control bleeding during surgery and avoid the need for transfusion.

While the author of an accompanying editorial believes more study is needed on the topic, lead author Dr. Bruce D. Spiess said the research points out risk for adverse outcomes "that no one had known about before."

"We are the first study to make this link," Spiess said. He calls the association "very surprising."

Death was more than five times more likely to occur in those who got the platelet transfusion as those who did not, and stroke was at least three times more likely.

Of the 1,720 patients analyzed, 284 got blood platelet transfusions during their coronary artery bypass graft surgery, an operation to improve blood flow to the heart by grafting a clean vessel from the leg or elsewhere near the heart to replace a blocked one.

The operation took about an hour longer for transfusion recipients -- five hours compared to 4.2 hours. And almost one-fifth of those who got the transfusion returned to surgery for more work, compared to just 2 percent of those who did not get transfused.

Hospital stays were longer for transfused patients, 12.5 days compared to 10.3.

The practice of transfusing blood during bypass surgery varies, Spiess said. "At some places, as many as 40 percent of patients get transfused, some as few as 1 to 3 percent. It just depends on the institution."

Platelet transfusion, as the name implies, involves giving only platelets, which help make clots and can help a person stop bleeding excessively. Red cell transfusions are what most people think of as a standard transfusion, Spiess said. Those are given to help the blood carry more oxygen.

While Spiess emphasizes the study does not prove cause and effect -- and that in fact the transfused patients might just have been sicker -- he said the study findings are reason to exercise caution. "Don't give these platelet transfusions unless you absolutely have to if the patient is bleeding," he suggested.

Why platelet transfusions seem boost the risk of problems, isn't known, but Spiess calls transfused platelets "troublemakers."

"When people get other people's platelets, it tends to increase the inflammatory processes, setting them up for stroke and possible other adverse events."

In the accompanying editorial, Dr. Walter Dzik, associate editor of the journal, said caution is needed not only in the excessive use of transfusions but also in the "overinterpretation of association studies." The topic needs more study over the coming years, he wrote.

But another expert, Dr. Neil Blumberg, a professor of pathology and laboratory medicine at University of Rochester Medical Center in New York, found the research to be strong. "I think it's going to turn out to be a landmark study because I think it's one of the first to look directly at the issue as to whether transfusion of platelets has potential new side effects that we hadn't been aware of."

"What Bruce's data say is, maybe we should be more conservative about using platelets until we know more," Blumberg said.

More information

To learn more about blood donation and transfusions, visit the American Association of Blood Banks.

(SOURCES: Bruce D. Spiess, M.D., professor, anesthesiology, Virginia Commonwealth University Medical Center, Richmond; Neil Blumberg, M.D., professor, pathology and laboratory medicine, University of Rochester Medical Center, Rochester, N.Y.; August 2004 Transfusion)