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Blood Transfusions Linked to Infection Risk in Hospitals

Hospitalized patients who had fewer blood transfusions had lower risks of infection, according to a large analysis. The results suggest that more conservative transfusion strategies could help reduce infection rates at health care facilities.

About 1 in every 20 hospital inpatients develops an infection related to their care. These infections can have devastating consequences — lengthening the time hospitalized and, in some patients, contributing to death. Strategies to reduce infections include using checklists, improving hand hygiene, and avoiding the use of urinary catheters.

One common inpatient therapy is transfusion of red blood cells. More than 37,000 units of red blood cells are transfused every day in the United States. Transfusions can replace blood lost during surgery or after a serious injury. Transfusions may also help people who are unable to make enough blood due to an illness, such as cancer or kidney failure. Transfusions are often given when patients have low levels of hemoglobin, an iron-rich protein in red blood cells. Normal hemoglobin levels range from about 14 to 17 g/dL (grams per deciliter) in men and 12 to 15 g/dL in women.

The risk of developing an infection from a blood transfusion is extremely low. Donated blood is carefully screened for infectious agents, such as viruses. However, when patients receive blood from a donor, their immune system may react to substances found in the stored donor blood, placing them at greater risk of infection from other sources.

A team led by Drs. Mary Rogers and Jeffrey Rohde of the University of Michigan set out to examine the association between transfusion strategies and health care-associated infections. The work was funded by NIH’s National Heart, Lung, and Blood Institute (NHLBI). Results were published April 2, 2014, in the Journal of the American Medical Association.

The scientists analyzed data from 18 randomized clinical trials that together included more than 7,500 patients. These trials compared liberal transfusion strategies (where patients received more blood) to restrictive transfusion strategies (where patients received less blood, generally only when their hemoglobin levels dropped below 7 or 8 g/dL or they had symptoms). The team examined the incidences of health care-associated infections, such as pneumonia, wound infection, and sepsis.

The risk of serious hospital-associated infections was about 17% when liberal transfusion strategies were used but only 12% with restrictive transfusion strategies. The researchers calculated that for every 1,000 patients in which transfusion is under consideration, 26 could potentially be spared an infection if restrictive strategies were used.

There were some differences, however, that depended on the clinical setting. In patients who underwent hip or knee surgery, or who already had sepsis, a restrictive transfusion strategy reduced the risk of infection by 30% or more. The risk of infection, however, was similar for the 2 transfusion strategies in patients with cardiac diseases, who were critically ill, had acute upper gastrointestinal bleeding, or for infants with low birth weight.

“Overall, the fewer the red blood cell transfusions, the less likely hospitalized patients were to develop infections,” Rohde explains. “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.”

— by Carol Torgan, Ph.D.