Blood, like any perishable product, has a ‘use by’ date. But should that date be changed?

A study of 9,000 heart surgery patients in the United States now suggests that using blood older than 2 weeks for transfusion ups a patient’s chances of blood poisoning and organ failure, making him or her 64% more likely to die than those who get newer blood (New England Journal of Medicine (NEJM) paper). Those given older blood had a 2.8% death rate during their stay in hospital, compared to 1.7% in those with fresher transfusions (Medical News Today).

“Blood should be classified as outdated earlier than current recommendations,” lead researcher Colleen Koch told New Scientist.

The current UK regulations state that blood can be stored for 28 to 49 days depending on the method of collection, processing and storage (The Blood Safety and Quality Regulations 2005). In the United States blood can be stored for up to 6 weeks, though the median storage time is 15 days (LA Times). Reducing that time period might make for safer blood supplies, but it would also seriously reduce the amount of blood available; bad news since blood is already in limited supply. “Fresher blood? Patients take what they can get” says MSNBC.

The better solution may be to do fewer transfusions, reserving them for emergency cases only. The LA Times says such policy shifts are already underway, along with other measures to limit transfusions, such as ‘blood scavenging’ during surgery and drugs that limit operative bleeding. An accompanying editorial in the NEJM discusses these issues.

FDA officials (who regulate blood guidelines in the United States) have been variously quoted as calling the study “provocative” (MSNBC) and “narrow and non-randomized” (LA Times). Regulations are unlikely to change soon.