About one in every 20 hospitalized patients develops an infection as a result of their care, but limiting blood transfusions to patients with low hemoglobin levels may decrease their risk for acquiring one, researchers have found.
Although donated blood is carefully screened for infectious agents and the likelihood of developing an infection from a transfusion is slim, some patients may react poorly to substances found in stored blood, increasing their risk for infection from other sources.
In the new study, Mary Rogers, PhD, from the Department of Internal Medicine at the University of Michigan, in Ann Arbor, and her colleagues conducted a systematic review and meta-analysis of 18 randomized clinical trials that included more than 7,500 patients. The experiments compared liberal transfusion strategies to restrictive approaches—generally when patients’ hemoglobin levels dropped below 7 g/dL or they had symptoms of anemia—and the associated risks for infections, such as pneumonia, mediastinitis and sepsis.
The researchers found that the chance for serious hospital-related infections was about 17% for patients in whom liberal transfusion strategies were used but only 12% for those treated with more restrictive triggers. They calculated that for every 1,000 patients in whom a transfusion is potentially warranted, 26 could potentially be spared an infection if transfusions were reserved for emergency situations.
The clinical setting had a substantial effect on the risk for infection. In patients who underwent hip or knee surgery, for example, or who already had sepsis, a restrictive strategy reduced the risk for infection by at least 30%. However, transfusion strategy did not appear to affect infection risk in patients with cardiac diseases, who were critically ill, had acute upper gastrointestinal bleeding and for infants with low birth weight.
“There’s been a huge shift in what we now know compared to what the prevailing medical knowledge has been,” said Dr. Rogers. “Many physicians don’t yet know about this problem and not too long ago many of them were giving two red blood cell units at a time thinking that it couldn’t hurt. But with some simple steps we now have the potential to limit serious infections, so I really hope that more doctors will adapt these restrictive strategies.”
The researchers published their findings in the Journal of the American Medical Association(2014;311:1317-1326). The study was funded by the National Heart, Lung, and Blood Institute.
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