Trauma patients with type O are more likely to die from hemorrhage than other blood types according to researchers from the Tokyo Medical and Dental University.
This retrospective observational study published in Critical Care included 901 trauma patients with injury severity scores >15.
The adjusted odds ratio for death for persons with type O blood when compared with all other blood types were as follows:
These findings indicate increased all-cause mortality, increased risk of death due to hemorrhage and to death due to traumatic brain injury among trauma victims with blood type O when compared to other blood types. These findings are in keeping with previously published studies which have found that persons with type O blood have decreased risk of deep venous thrombosis  and increased risk of GI hemorrhage , obstetrical hemorrhage , and bleeding associated with anticoagulant usage  when compared to other blood types.
The study investigators propose that this discrepancy may be due to decreased von Willebrand factor levels in persons with blood type O.
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