Severe injury patients with an O blood type are almost three times as likely to die than patients with any other blood type, according to a study recently published in the journal Critical Care.
A team of researchers led by Wataru Takayama from Tokyo Medical and Dental University Hospital, Japan, compared death rates between severe injury patients of the different blood groups – A, B, O, and AB. Over 900 patients admitted to one of two emergency critical care medical centers in Japan between 2013 and 2016 were involved in the study.
Whereas type O patients faced a death rate of 28 percent, those of all the other blood groups combined faced one of 11 percent.
The researchers suspect this startling contrast comes down to something called the von Willebrand factor, a blood clotting agent, which people with the blood type O have in lower levels than those with other blood types. The relative deficit in von Willebrand factor could increase rates of hemorrhage – when blood escapes from a ruptured blood vessel – and, therefore, increases the risk of fatality in cases of severe injury.
While there is nothing much that can be done to change this inconvenient fact, Takayama and his team say that recognizing it can help emergency care staff control the intensity of trauma critical care to limit the risk as much as possible. It is also something to consider when administering emergency transfusions, especially as O negative is considered to be the universal donor. It's the blood type most in demand because it is compatible with all other blood types, which means anyone can receive a blood transfusion or donation from someone with type O.
"Our results also raise questions about how emergency transfusion of O type red blood cells to a severe trauma patient could affect homeostasis, the process which causes bleeding to stop, and if this is different from other blood types," Takayama said in a statement. "Further research is necessary to investigate the results of our study and develop the best treatment strategy for severe trauma patients."
More research is needed to confirm the von Willebrand theory as well as to see if and what differences there are between the other blood groups (A, B, and AB), not to mention the differences (if any) between negative and positive blood groups. The authors also warn that the participants were limited to Japanese patients and, therefore, may not apply to all ethnic groups.
In the UK and US, type O is the most common blood type, with roughly 47 percent of the UK population having either O positive (40 percent) or O negative (7 percent). In the US, roughly 45 percent of the population has either an O positive (38 percent) or O negative (7 percent).
While it appears it may increase the risk of hemorrhage, it also lessens the threat of deadly clotting.