Blood type O is associated with high death rates in severe trauma patients, according to a new study published in the open access journal Critical Care that involved 901 Japanese emergency care patients. The study was conducted by researchers at Tokyo Medical and Dental University Hospital in Japan. Severe trauma patients, those with an injury that has the potential to cause long-term disability or death, with blood type O, had a death rate of 28%, compared to a rate of 11% in patients with other blood types, according to the study. "Recent studies suggest that blood type O could be a potential risk factor for haemorrhage (bleeding in large amounts). 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," said Wataru Takayama, the corresponding author of the study. Researchers found that patients with blood type O have been shown to have lower levels of Von Willebrand factor (VWF), a blood clotting agent, than those with other blood types. VWF is a blood glycoprotein involved in haemostasis. Also, lower levels of VWF may be linked to higher levels of haemorrhage. The team suggests that a lower level of VWF is a possible explanation for the higher death rate in trauma patients with blood type O. Takayama said: "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. Further research is necessary to investigate the results of our study and develop the best treatment strategy for severe trauma patients." The authors relied on data from medical records of 901 patients with severe trauma to reach their findings, who had been transported to either of two tertiary emergency critical care medical centres in Japan during 2013 to 2016. Takayama urged that further research is needed to understand if the findings apply to other ethnic groups, since all the patients whose data was analysed in this study were Japanese. Additionally, there was no evaluation of the impact of the individual blood types A, AB, or B on severe trauma death rates. Instead, the researchers compared type O to non-O blood type, which may have diluted the effect of individual blood types on patient's survival.
