The more red blood cells patients receive during a blood transfusion, the greater their risk of infection, according to an analysis of previously published studies.
Researchers with the University of Michigan Health System and VA Ann Arbor Healthcare System analyzed 21 randomized controlled trials and found the association was most pronounced in elderly patients undergoing hip or knee surgeries. These patients had a 30% lower risk of infection when fewer transfusions were used.
Overall, for every 38 hospitalized patients considered for a red blood cell transfusion, one patient would avoid a serious infection if fewer transfusions were used, the researchers reported in the April 2 issue of the Journal of the American Medical Association.
The authors evaluated all healthcare-associated infections that were reported after receiving donor blood in the randomized trials. These included serious infections such as pneumonia, bloodstream infections and wound infections.
The fewer the red blood cell transfusions, the less likely hospitalized patients were to develop infections, lead author Jeffrey M. Rohde, MD, assistant professor of internal medicine in the division of general medicine at the U-M Medical School, said in a news release.
This is most likely due to the patients immune system reacting to donor blood [known as transfusion-associated immunomodulation]. Transfusions may benefit patients with severe anemia or blood loss; however, for patients with higher red blood cell levels, the risks may outweigh the benefits.
Risks of additional hospital infections were particularly high for patients who already had sepsis. They were twice as likely to develop additional infections when they received more transfusions.
About 14 million red blood cell units were used in the U.S. in 2011, most often in hospitals. Lower hemoglobin thresholds are recommended by recent guidelines, but only 27% of hospitals that responded to the National Blood Collection and Utilization Survey reported following these guidelines after surgery, according to the news release. Only 31% of hospitals reported having a blood management program that aims to optimize the care of patients who might need a transfusion.
Study abstract: http://jama.jamanetwork.com/article.aspx?articleid=1853162