Blood Transfusions Increase Risk of Infections

The more red blood cell (RBC) transfusions a patient receives, the greater their risk of contracting healthcare associated infections (HAIs), according to a new study.

Researchers at the University of Michigan Heath System (U-M; Ann arbor, USA) and the US veterans association (VA) Ann Arbor Healthcare System (MI, USA) reviewed 21randomized trials involving 8,735 patients to evaluate whether RBC transfusion thresholds are associated with the risk of infection, and whether risk is independent of leukocyte reduction. Participants were classified as belonging to restrictive or liberal transfusion strategies. The main outcome was incidence of HAIs such as pneumonia, mediastinitis, wound infection, and sepsis.

The results showed that the pooled risk of all serious infections was 11.8% in the restrictive group and 16.9% in the liberal group. The number needed to treat (NNT) with restrictive strategies to prevent serious infection was 38, even with leukocyte reduction. A restrictive hemoglobin threshold of less than 7 g/dL resulted in a relative risk (RR) of 0.82, with a NNT of 20. When categorized by type, RR was 0.7 in patients undergoing orthopedic surgery and 0.51 in patients presenting with sepsis. There were no significant differences in the incidence of infection for patients with cardiac disease, the critically ill, acute upper gastrointestinal bleeding, or for infants with low birth weight. The study was published in the April 1, 2014, issue of the Journal of the American Medical Association (JAMA).

“The fewer the red blood cell transfusions, the less likely hospitalized patients were to develop infections,” said lead author Jeffrey Rohde, MD, of the division of general medicine at U-M. “This is most likely due to the patient's immune system reacting to donor blood. 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.”

Transfusion-associated immune-modulation (TRIM) has been recognized in people who had kidney transplantation or have had multiple miscarriages. Some studies have shown that because of this immune depression, blood transfusions increase the risk of infections and cancer recurrence, while other studies have not. The impact transfusion has on infection and tumor recurrence is thus not well understood. The Blood Products Advisory Committee of the US Food and Drug Administration (FDA) recommends that all transfused blood products undergo leukocyte reduction in order to offset the contribution of donor white blood cells to immune suppression.

Related Links:
University of Michigan Heath System
VA Ann Arbor Healthcare System