Blood that has been stored for 2 weeks or more before being used in transfusions for critically ill patients does not appear to cause adverse effects, report US researchers.
The findings show that patients who receive transfusions containing at least 1 unit of red blood cells (RBCs) aged 14 days or more are at no increased risk for complications, nosocomial infections, or morbidity compared with their peers who receive "fresh" RBCs aged less than 8 days, report researchers.
"This evidence contrasts with previous results suggesting that older RBCs may be harmful," say Leanne Clifford and colleagues from the Mayo Clinic in Rochester, Minnesota, who reported their results at the Anesthesiology 2012 Annual Meeting in Washington DC, USA.
Indeed, some of the results indicated fresh blood may worsen outcomes for these patients.
The team conducted a retrospective cohort study of 99 patients who received a transfusion of exclusively fresh RBCs and 99 matched patients who received transfusions that included at least 1 unit of RBCs that had been stored for 2 weeks or more.
Data for outcomes were adjusted "meticulously," for factors including number of units of RBCs transfused, patient age, and primary body system disease, say the authors.
Rates of overall complications post-transfusion were comparable, remark Clifford et al, at 1% among patients who received fresh blood and 2% among those whose transfusions contained older blood.
Morbidity outcomes - defined as a change in sequential organ failure assessment scores - were also comparable between fresh and stored blood recipients, at 8.6 and 8.0, respectively. Similarly, corresponding lengths of stay in the intensive care unit did not differ significantly between the groups, at 1.8 and 1.6 days.
However, rates of nosocomial infection tended toward being higher among patients who received fresh as opposed to stored blood at 9.1% versus 2.0%, and overall mortality rates were higher in the former than the latter group, at 20.2% versus 9.1%.
Commenting on the research, Joel Zivot (Emory University, Atlanta, Georgia) who moderated the session at which the research was presented said that the study poses a "timely and important question," but that future studies into the exact timing of transfusion would need to be undertaken.
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