FRIDAY, Oct. 2 (HealthDay News) -- People who've suffered severe trauma and are given a major transfusion of red blood cells that have been stored for a month or longer are twice as likely to die as those who receive fresher red blood cells, U.S. researchers have found.

In a study of 202 severe trauma patients who were treated with five or more units of red blood cells, researchers found that even one unit of red blood cells stored more than 28 days doubled the incidence of deep vein thrombosis and increased death secondary to multiple organ failure.

The increased risk of death persisted for up to six months after the transfusion, a finding that's consistent with previous studies of cardiac surgery patients. The new study, published online Sept. 21 in Critical Care, shows that the risk of adverse complications can be reduced if doctors give fresh red blood cells to severe trauma patients who require major transfusions for life-saving procedures, the researchers said.

"The preferential use of younger red blood cells to critically ill patients has the potential to increase waste due to outdating," Philip Spinella, a pediatric intensivist at Connecticut Children's Medical Center in Hartford, said in a news release from the journal's publisher. "Since blood is often a scarce resource, this is important, and methods need to be developed to minimize waste while providing the most efficacious and safe blood product for a given patient."

Spinella and his colleagues wrote that their "findings should encourage research into the effects of old blood and coagulation in critically ill patients."

"With the widespread use of red blood cell transfusion for critically injured patients, this study has the potential to cut deaths in hospitals around the world," they wrote.

More information

The U.S. National Heart, Lung, and Blood Institute has more about blood transfusion.