Photo by Elise Amendola
Results of a large, international study suggest the risk of death after transfusion is not significantly affected by the age of blood transfused.
The median storage duration for the fresher blood used in this study was 11 days, and the median storage duration for older blood was 23 days.
The rate of death was 9.1% for the patients who received fresher blood and 8.8% for patients who received older blood (P=0.38).
Researchers reported these and other results from this study in NEJM.
“It’s been a contentious issue, but our study finally puts an end to the question about whether stored blood could be harmful and fresher blood would be better,” said study author Nancy Heddle, of McMaster University in Hamilton, Ontario, Canada.
“Our study provides strong evidence that transfusion of fresh blood does not improve patient outcomes, and this should reassure clinicians that fresher is not better.”
For this study, Heddle and her colleagues enrolled 31,497 adult patients treated at hospitals in Australia, Canada, Israel, and the US. However, 6761 patients did not meet all the enrollment criteria and were excluded after randomization.
A and O blood types
The researchers’ primary analysis included only patients with type A or O blood. Of these 20,858 patients, 6936 were assigned to receive blood stored for a shorter period, and 13,922 were assigned to receive blood stored for a longer period.
The mean storage duration was 13.0 ± 7.6 days in the short-term group and 23.6 ± 8.9 days in the long-term group. The median storage duration was 11 days (range, 8-16) and 23 days (range, 16-31), respectively.
The rate of death was 9.1% (n=634) in the short-term storage group and 8.7% (n=1213) in the long-term storage group. The odds ratio was 1.05 (95% CI, 0.95 to 1.16; P=0.34).
All blood types
The researchers also analyzed patients with any blood type. Of the 24,736 patients studied, 8215 were assigned to receive blood stored for a shorter period, and 16,521 were assigned to receive blood stored for a longer period.
The mean storage duration was 13.4 ± 7.7 days in the short-term group and 23.6 ± 8.9 days in the long-term group. The median storage duration was 11 days (range, 8-17) and 23 days (range, 16-31), respectively.
The rate of death was 9.1% (n=750) in the short-term storage group and 8.8% (n=1446) in the long-term storage group. The odds ratio was 1.04 (95% CI, 0.95 to 1.14; P=0.38).
The researchers said the overall results were similar to those observed in 3 pre-specified high-risk subgroups—patients undergoing cardiovascular surgery, individuals admitted to intensive care, and patients with cancer.
“Advances in blood storage now allow blood to be stored up to 42 days before transfusion, and the usual practice is to use up the blood that has been in storage the longest,” said study author John Eikelboom, MD, also of McMaster University.
“But because there are biochemical, structural, and functional changes in the blood during storage, there had been concerns about the use of ‘older’ blood. This study reassures us that aging is not bad—even for blood.”
The findings of this study are in line with the recently released AABB recommendations on blood transfusion.
