People with the most common blood type, type O, may be at higher risk of death after suffering severe injuries because they’re more likely to have major bleeding, a new study suggests.
While the study is preliminary, Japanese researcher Dr. Wataru Takayama said the “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.”
According to the American Red Cross, type O is the most common blood type, found in about 45 percent of white people, and more than 50 percent of blacks and Hispanics. It’s also the most useful blood type for transfusions because type O negative blood is suitable for use by any recipient — it’s the “universal red cell donor” type.
But the research team from Tokyo Medical and Dental University Hospital might have found one downside to type O. Their research focused on the medical records of more than 900 patients treated for severe trauma.
Death rates were 28 percent for those with blood type O but just 11 percent for those with other blood types, the researchers reported May 1 in the journal Critical Care.
The research can’t prove cause-and-effect, but “recent studies suggest that blood type O could be a potential risk factor for hemorrhage (bleeding in large quantities),” Takayama said in a journal news release.
People with blood type O have lower levels of a certain blood clotting agent than those with other blood types. And this may be why people with blood type O are more likely to have major bleeding after a severe injury, the study authors said.
“Loss of blood is the leading cause of death in patients with severe trauma, but studies on the association between different blood types and the risk of trauma death have been scarce,” Takayama added. “We wanted to test the hypothesis that trauma survival is affected by differences in blood types.”
The authors noted that since all the patients in the study were Japanese, further research is needed to determine if this study’s findings apply to other racial and ethnic groups.