A study of heart surgery patients has found that those getting transfusions of blood more than two weeks old had higher chances of dying or developing complications.
Cleveland Clinic researchers checked the records of 6,000 patients who had heart valve replacement or heart bypass surgery from 1998 through 2006.
Those who were given blood that had been stored for 14 days or more had lower survival rates and developed more complications than those who were transfused with fresher blood.
Similar results have been reported in smaller studies that looked at other types of patients.
The Food and Drug Administration allows whole blood to be stored for up to six weeks.
The study's lead author, Doctor Colleeen Gorman Koch, has said that a more rigorous study is under way that could have enough scientific weight to change the FDA rule.
The study appears in this week's edition of the New England Journal of Medicine.
