Impact of ABO blood group on mortality in trauma patients: A systematic review

Background: Haemorrhage is a significant cause of death in trauma patients. There is evidence that individuals with blood group O have higher rates of non -traumatic haemorrhage. It has been suggested that blood group O may be associated with higher mortality in trauma, however existing evidence is limited and conflicting. Objective: A systematic review was conducted to evaluate the impact of ABO blood group on mortality in trauma patients. Methods: MEDLINE via OVID, the Cochrane library and grey literature were searched to identify studies investigating the effect of ABO blood group on mortality of trauma patients admitted to hospital. PRISMA guidelines were followed throughout, study quality was assessed using CASP checklists and certainty of evidence was evaluated using GRADE. Meta -analysis was precluded by significant study heterogeneity. Results: 180 relevant records were screened and seven studies met inclusion criteria, representing 12,240 patients. Two studies found that there was a higher mortality in blood group O compared to other ABO groups. Included studies had substantial variability in methods and population. Study quality was variable with certainty of evidence rated as very low. Conclusions: There is insufficient evidence to definitively establish an association between mortality and ABO group in trauma patients. In an age of increasingly individualised care, there is a need to determine the existence and cause for any association through further studies across multiple settings, trauma mechanisms and populations.