Overuse of blood transfusions may be linked to a greater risk of infections such as pneumonia, bloodstream infections and wound infections, according to a U.S. study released Tuesday that urged doctors to use transfusions more sparingly.

Transfusions are often used for anemia or during surgery to make up for blood loss, with approximately 14 million units of red blood cell (RBC) transfused in 2011 in the United States.

Lower hemoglobin thresholds are recommended, but only 31 percent of U.S. hospitals reported having a blood management program, according to the study published in the Journal of the American Medical Association.

In order to evaluate their association with the risk of health care-associated infection, researchers from the University of Michigan and VA Ann Arbor Healthcare System analyzed 21 randomized controlled trials with 8,735 patients who underwent transfusion.

The researchers found that for those patients receiving the restrictive transfusion strategies, the risk of infection was 11.8 percent, and for patients receiving the liberal transfusion strategies, was 16.9 percent.