Red blood cells (RBCs) undergo numerous changes as they are stored – some of which may impair their ability to increase oxygen delivery, which theoretically could affect clinical outcomes in patients needing transfusions. While earlier observational studies have suggested that the age of stored blood increases mortality risk in these patients, two new studies published in The New England Journal of Medicine report that transfusion of “newer” red cells – those stored for a shorter period of time – was not associated with better outcomes than transfusion of “older” blood.
While the two randomized clinical trials were conducted in two distinct patient populations, the findings were consistent. The first study, known as the Red-Cell Storage Duration Study (RECESS), examined patients 12 years or older who were undergoing complex cardiac surgery and were likely to need an RBC transfusion. The second study, the Age of Blood Evaluation (ABLE) pilot trial, looked at the impact prolonged storage of RBCs had on critically ill adult patients in tertiary care intensive care units who needed a transfusion.
Neither study found any significant differences in the measured patient outcomes between fresh blood and blood that had been stored for a longer duration.
“The RECESS study suggests that there are no advantages to patients when the more-difficult-to-procure fresher blood is provided, compared with the use of standard blood,” Paul M. Ness, MD, an investigator on the RECESS study and professor of pathology at Johns Hopkins University Hospital, told ASH Clinical News. “The current standard of care usually provides blood that has been stored for around three weeks.”
In the United States, storage systems are allowed to store blood for up to 42 days, with most facilities adopting a “first in, first out” inventory management approach to minimize waste of blood components. Fresh blood is even more difficult to procure in larger transfusion centers: Suppliers typically send fresh blood to smaller or more remote centers first, and unused blood is sent back for redistribution to larger centers, increasing the likelihood that patients at these larger facilities will receive blood that has been stored for a longer time period.
The findings from these latest clinical trials seem to suggest this current practice is sound, both in terms of preserving blood supply and providing good patient outcomes.
The RECESS trial included 1,481 cardiac surgery patients from 33 hospitals in the United States. Patients were randomly assigned to receive either red blood cell units stored for ≤10 days (n=538) or units stored for ≥21 days for all of their intraoperative and postoperative transfusions.
Investigators then measured the change in each patient’s Multiple Organ Dysfunction Score (MODS) and compared the scores from before surgery with scores taken seven days after surgery (or until the patient’s time of death or discharge, whichever came first).
Mean change in MODS score at seven days (the study’s primary outcome) was 8.5±3.6 points in the short-term storage group and 8.7±4.0 points in the longer-term storage group (p=0.44). Even after comparing the change in MODS for only post-operative scores, they found no significant differences between the two groups.
There were also no significant differences between the groups for all-cause mortality, 28-day change in MODS, length of hospital stay, or length of ICU stay.
In the ABLE trial, investigators, led by Jacques Lacroix, MD, from Centre Hospitalier Universitaire Sainte-Justine in Montreal, assigned critically ill adults from 64 centers in Canada and Europe to receive either red blood cells stored for <8 days (n=1,206) or standard-issue red blood cells (n=1,206). Red blood cells were stored a median of 6.1±4.9 days in the fresh-blood group, and 22.0±8.4 days in the standard-blood group.
At 90 days, rates of all-cause mortality (the study’s primary endpoint) was 37 percent in the fresh-blood group and 35.3 percent in the standard-blood group (absolute risk difference = 1.7 percentage points; 95% CI –2.1 to 5.5).
In the survival analysis, Dr. Lacroix and investigators found no significant differences between the two groups (hazard ratio = 1.1; 95% CI 0.9–1.2; p=0.38). They also noted no significant between-group differences in secondary outcomes, such as major illness, length of hospital stay, transfusion reactions, or duration of respiratory, hemodynamic, or renal support.
While the results of both studies affirm current practices, Dr. Ness said it’s still unclear whether blood that is closer to its expiration date of 42 days could affect clinical outcomes. Animal studies at the National Institutes of Health have suggested that very old blood can worsen outcomes in animals with infection, he noted.
He also said it is not yet known whether new blood storage systems currently being studied will have an impact on clinical outcomes. “It’s possible these new systems could increase the post-transfusion survival of red cells or provide better oxygen delivery in critically ill patients,” Dr. Ness added.
- Steiner ME, Ness PM, Assmann SF, et al. Effects of red-cell storage duration on patients undergoing cardiac surgery. N Engl J Med. 2015;372:1419-29.
- Lacroix J, Hebert PC, Fergusson DA, et al. Age of transfused blood in critically ill adults. N Engl J Me 2015;372:1410-8.