New research has found that people with blood type O may be at increased risk of dying from severe trauma - an injury that has the potential to cause long-term disability or death.
The study involving more than 900 Japanese emergency care patients showed that severe trauma patients with blood type O had a death rate of 28 per cent, compared to a rate of 11 per cent in patients with other blood types.
To understand the impacts of blood types on trauma patients, the study, published in the journal Critical Care, compared type O to non-O blood type.
"Recent studies suggest that blood type O could be a potential risk factor for haemorrhage (bleeding in large quantities)," said the corresponding author of the study Wataru Takayama from the Tokyo Medical and Dental University Hospital in Japan.
"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. We wanted to test the hypothesis that trauma survival is affected by differences in blood types," Takayama added.
Patients with blood type O have been shown to have lower levels of von Willebrand factor, a blood clotting agent, than those with other blood types.
Lower levels of von Willebrand factor may be linked to higher levels of haemorrhage.
The authors suggest that a lower level of the factor is a possible explanation for the higher death rate in trauma patients with blood 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.
"Further research is necessary to investigate the results of our study and develop the best treatment strategy for severe trauma patients," Takayama added.