Red Blood Cell Storage Lesion and Adverse Clinical Outcomes: Post Hoc Ergo Propter Hoc?

Since the publication in 2008 of a retrospective
analysis by Koch et al.9 reporting that subjects
transfused with red blood cell units stored for
longer than 14 days, were more likely to die in the
hospital, there has been an intense debate about
the topic whether transfusion of older blood is as
beneficial as transfusion of fresher blood. Several
studies have found suggestive evidence of various
adverse consequences after transfusion of older
blood such as an increase in length of hospital stay,
postoperative infections, prolonged mechanical
ventilation, multiple organ failure and mortality10,11.
Nevertheless, recently published meta-analyses and
reviews indicate that there are many studies that do
not report such association between RBC storage
age and adverse clinical outcomes11,12,13,14. Yet, it is
not currently known if clinical outcomes are affected
by the age of transfused blood and uncertainty
remains regarding the clinical importance of RBC
storage duration and when “new” blood becomes
“old” blood.