Transfusing red blood cells that have been stored for 21 days or more does not increase the risk of complications following cardiac surgery, according to a new U.S. trial involving more than 1,000 patients.
“It really doesn’t look like it makes much difference clinically,” said the chief author, Dr. Marie Steiner, a professor of pediatrics at the University of Minnesota. She told Reuters Health in a phone interview that the findings will probably put “a significant damper” on people pushing for fresher blood in such instances.
It comes on the heels of the larger ABLE study, reported by the Journal last month, which showed no benefit for fresher blood among intensive care patients.
“It’s reassuring,” said Dr. Dean Ferguson, a senior scientist at The Ottawa Hospital in Canada and a coauthor of the ABLE study, who was also involved in an earlier test of new versus old blood in premature infants that produced the same result.
“So now there are three major studies showing no difference,” he told Reuters Health.
Concern about stored blood has been around for nearly two decades.
“It’s a major issue for the blood providers because a lot of the observational work, less rigorous research and animal studies were showing that fresh was better,” said Dr. Ferguson. “They’ve been feeling that pressure for the last few years. That’s why these large trials are needed and helpful. The fact that there’s absolutely no difference is a relief for them.”
All of the 1,098 patients in the new study, from 33 U.S. hospitals, were age 12 and older. Among those who got a transfusion, the median number of units transfused was three.
Half the patients were randomly assigned to receive blood stored for 10 days or less, while the rest received units stored for at least 21 days.
“In the United States, the average storage duration of transfused red cells is 17.9 days,” the researchers said.
To assess any potential impact, they looked for a change in the Multiple Organ Dysfunction Score (MODS) from before surgery at the seventh postoperative day. Patients who died during that period received a maximum score of 24.
Among the components making up the MODS score, only the hepatic component, which uses total serum bilirubin, showed a significant difference between the groups (P<0.001). “This finding is not unexpected, because red cells hemolyze during storage,” the researchers note.
When they excluded patients who had received a unit that was older or newer than they had been assigned to receive, the outcome scores were still comparable.
Mortality rates were essentially the same — 15 died in the short-term-storage group (2.8%) versus 11 in the long-term group (2.0%) (P=0.43).
On average, people in both groups suffered 1.6 severe adverse events (p=0.75).
Only when it came to a hepatobiliary disorder was a different rate seen, with 5% in the short-term storage group having the problem versus 9% in the long-term group (P=0.02).
“This finding was due entirely to the fact that fewer participants in the shorter-term storage group had hyperbilirubinemia,” the researchers said.
So when it comes to the idea that fresher blood will give better outcomes, Dr. Steiner said, “it surely looks like it ought to be this way in the lab and in dogs, but if you look at the question in a large group of people, it just isn’t that important.”
“My bias is that there’s so much else going (in trauma and cardiac cases) on that the contribution of the red cells is probably not that much,” she said. “You’re talking about people who have been hit by a truck or are having their chest split open. You ask how can one or two units of blood make that much difference. It probably doesn’t.”
The trial was funded by the National Heart, Lung, and Blood Institute.
SOURCE: N Engl J Med 2015