Compared with standard-issue red cells, transfusion of “fresh” red cells stored for fewer than 8 days failed to improve 90-day mortality in a large international study of adult ICU patients, which was reported online April 9 in the New England Journal of Medicine.

“Current regulations permit the storage of red cells for up to 42 days, but prolonged storage has been associated with changes that may render cells ineffective as oxygen carriers and that lead to the accumulation of substances that have untoward biologic effects,” said Dr. Jacques Lacroix of the University of Montreal and his associates.

A recent meta-analysis suggested that transfusion of older red cells was associated with a 16% increase in mortality among critically ill patients, but several randomized trials have failed to document any adverse effects on oxygenation, immunologic, or coagulation factors. Dr. Lacroix and his associates performed the Age of Blood Evaluation (ABLE) study, a prospective, blinded clinical trial involving ICU patients enrolled during a 5-year period at 64 medical centers in Canada, the United Kingdom, France, the Netherlands, and Belgium. A total of 1,211 participants were randomly assigned to receive “fresh” blood stored for an average of 6 days and 1,219 to receive standard blood stored for an average of 22 days – a difference that the investigators deemed statistically and clinically significant.

The primary outcome measure, 90-day all-cause mortality, was 37% in the fresh-blood group and 35% in the standard-blood group, a nonsignificant difference. There also were no significant differences in mortality between the two study groups in any of several subgroup analyses based on patient age; the number of units transfused; baseline APACHE II scores; major comorbidities; duration of respiratory, hemodynamic, or renal support; length of ICU stay; or length of hospital stay, Dr Lacroix and his associates said (N. Engl. J. Med. 2015 April 9 [ doi:10.1056/NEJMoa1500704 ]).

“These findings have important implications for the critical care and blood transfusion communities. We surmise that the use of fresh red cells is not justified at this time. We might also infer that changes to red cells or the storage medium that have been documented in many laboratory studies may have limited clinical consequences,” they noted.

This trial was supported by the Canadian Institutes of Health Research, several other Canadian and French government agencies, and Sanquin Blood Supply. Dr. Lacroix reported having no financial disclosures; his associates reported ties to AKPA Pharma, Roche Diagnostics, GlaxoSmithKline, Novartis, and Amgen.