TUESDAY, Oct. 5, 2004 (HealthDayNews) -- Giving blood transfusions to counter anemia in patients hospitalized with heart attacks or other acute coronary problems may do more harm than good, a study finds.
Transfused patients were more likely to die or have a heart attack within 30 days than those who did not get blood, according to the review that analyzed data from three studies of more than 24,000 patients.
The danger appears to be concentrated in patients with moderately high anemia, said Dr. Sunil V. Rao, assistant professor of medicine at the Duke Clinical Research Institute in Durham, N.C., and lead author of the report.
The measure he used is hematocrit, the percentage of whole blood that consists of red cells. A normal hematocrit is in the neighborhood of 40, Rao said. Anemia is a lower-than-normal number of red blood cells.
"Our study shows that for these patients, a hematocrit value of 25 is the threshold," Rao said. "Above that, giving a transfusion appears to worsen the situation. Below that, it seems to help."
The Duke study appears in the Oct. 6 issue of the Journal of the American Medical Association.
Overall, the study found that 8 percent of the anemic heart patients who got transfusions died within 30 days, compared to 3.08 percent of patients who didn't get blood. The 30-day incidence of heart attack was 25.16 percent for transfused patients, and 8.16 percent for those who did not get blood. The combined risk of heart attack and/or death was 29.24 percent for transfused patients, compared to 10.02 percent for those who didn't get a transfusion.
Rao added that a carefully controlled study of transfusions in hospitalized heart patients is needed to guide treatment because the three trials he reviewed looked at overall treatment of patients, without singling out the effects of transfusions.
Dean A. Fergusson, assistant professor of medicine at the University of Ottawa and co-author of an accompanying editorial in the journal, agreed that more research on transfusions for anemic heart patients is needed.
"We have to be cautionary when it comes to such observational research," Fergusson said, referring to Rao's review. "In the end, you need large randomized trials to see if transfusions help or hurt patients in certain ranges of anemia."
One earlier study found that transfusions benefited such patients, Fergusson noted.
Rao said there are indications that physicians "are being very aggressive with transfusions."
"The results of our analysis suggest that physicians should look at the whole patient and not just the blood count number when considering whether or not to transfuse someone," he said. "The rule is to first do no harm. If patients are anemic but otherwise stable, they should not be transfused just to get them up to a certain hematocrit level."
Cardiologists should consider alternative treatments, such as erythropoeitin, a hormone that stimulates red blood cell production and is available in several genetically engineered products, both Rao and Fergusson said.
If a transfusion is given, it should be done moderately, one unit at a time, both said. Published guidelines call for that measured approach, but "the problem is that physicians don't pay attention to the guidelines," Rao said.
The Duke researchers are trying to get funding for a controlled study that could resolve the issue. They are preparing two grants applications, one to the National Institutes of Health and the other to Amgen, a biotechnology company that markets an erythropoeitin product, Rao said.
The National Library of Medicine has more on anemia and its treatment.