Patients who receive blood stored for 29 days or longer -- well within U.S. standards -- are twice more likely to get a hospital-acquired infection as those getting newer blood, according to media reports Wednesday.

Researchers at Cooper University Hospital in Camden, New Jersey, drew the conclusion after tracking 422 patients hospitalized in an intensive care unit who were given blood transfusions from July 2003 to September 2006.

If the patients got blood stored 29 days or more, they developed blood stream infections, pneumonia, urinary tract infections, heart valve infections, sepsis and other infections at twice the rate of patients getting blood stored for up to 28 days.

The blood itself was not infected, but the stored blood's release of chemical agents called cytokines may have affected the recipients' immune systems, rendering them more susceptible to infections, said Dr. Raquel Nahra of Sparks Regional Medical Center in Fort Smith, Ark.

U.S. Food and Drug Administration regulations allow for blood to be stored up to 42 days before it must be discarded. The average age of blood used in U.S. transfusions is around 17 days.

The researchers did not endorse shortening the 42-day policy, saying that could cut the amount available in the blood supply.

(Agencies via Xinhua October 30, 2008)