Study of effectiveness of old blood good news for blood providers

A new study out of McMaster University puts to bed years of debate over whether or not "fresher" blood is better for transfusions and surgeries, researchers say.

The study, which was published in the New England Journal of Medicine today, affirms the practice of blood providers to use blood that's up to 42 days old, says Nancy Heddle, lead author and professor emeritus of medicine for McMaster's Michael G. DeGroote School of Medicine.

"For blood suppliers, it's really good news," Heddle told CBC News.

The study focused on 31,497 adult patients from hospitals in Australia, Canada, Israel, and the U.S., and found that having a transfusion with the freshest blood did not reduce the proportion of patients who died in hospital. She said.

It allows them to stock up. Blood suppliers are happy to see these results.-NancyHeddle, study author

The mortality rate for those patients was 9.1 per cent with people receiving the freshest blood, and 8.7 per cent among those receiving the oldest blood. "There was no significant difference when looking at the patients' blood type, diagnosis, hospital or country," a news release about the study reads.

Heddle says that for about a decade, debate has raged over whether or not blood providers should keep plasma for shorter periods, because blood undergoes what's called "storage lesion" over time. Basically, that means its cells start to have an odd shape, and undergo biochemical reactions.

This study, she says, shows that older blood is nonetheless still viable which is important, seeing as suppliers often see shortages several times a year.

"It allows them to stock up. Blood suppliers are happy to see these results," she said and it's worth noting that the study was funded by the Canadian Institutes of Health Research, Canadian Blood Services and Health Canada.