To get a handle on possible links between blood age and infection risk among transfusion patients, Nahra and her colleagues analyzed records concerning 422 transfusion patients -- average age 66 -- who had been admitted to a single hospital intensive care unit between 2003 and 2006.
On average, the blood on hand at the ICU was 26 days old, while 70 percent of all the available blood was more than 21 days old.
Nahra and her team tracked the age of the first unit of blood each patient received, as well as the age of the oldest unit of blood they received.
The research team found that, following transfusion, 11 percent of the patients died, while 57 patients went on to develop one or more serious infections, including pneumonia, upper respiratory infection, sepsis and/or shock.
Specifically, 32 patients developed a single infection, 21 developed two such infections, and four patients developed three infections.
Patients who received blood transfusions with units of blood that had been packed for 29 days or longer were found to be twice as likely to develop such an infection as those getting blood stored for 28 days or less.
The age of the oldest unit of blood used during any transfusion was the factor most strongly linked to infection risk -- although the age of the first unit of blood used was also associated with an increased risk, the study found.
Despite the apparent infection association, no link was found between receiving a transfusion of older blood and a greater risk for death.
Noting that hospitals often use the oldest blood on hand first to minimize waste, Nahra and her team concluded that more studies are needed to identify the ideal storage period for blood, to protect against infection risk.
She noted that, as a practical matter, hospital patients cannot routinely request "fresher blood."
All rights reserved