A transfusion with the freshest blood did not reduce the proportion of patients who died in hospitals, according to a study published in the New England Journal of Medicine.
The study included almost 31,500 patients at six hospitals in Australia, Canada, Israel and the United States.
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Here are four insights:
1. The study found the mortality rate was 9.1 percent for people receiving the freshest blood, and 8.7 percent among those receiving the oldest blood.
2. There was no significant difference when looking at the patients' blood type, diagnosis, hospital or country.
3. Nancy Heddle, lead author and a professor emeritus of medicine for McMaster's Michael G. DeGroote School of Medicine, also said the results are good news for blood suppliers because having a supply of stored blood helps to ensure that blood is available when needed.
4. More than 40 previously published studies have failed to provide an adequate answer to this question of fresh versus old blood, noted John Eikelboom, a co-principal investigator of the study and professor of medicine of the Michael G. DeGroote School of Medicine in Ontario, Canada.
"Blood transfusions are a common medical intervention," he said in a statement. "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. 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."