INTRODUCTION: Previous studies suggested that type O blood may be associated with increased mortality and/or thrombotic complications among trauma patients. The purpose of this analysis was to evaluate the relationship between endogenous blood type, mortality, and complications among patients receiving massive transfusions, using data from the Pragmatic Randomized Optimal Platelet and Plasma Ratios trial. MATERIALS AND METHODS: This was a secondary analysis of the Pragmatic Randomized Optimal Platelet and Plasma Ratios trial that included patients with the reported blood type (A, AB, B, or O) data. Outcomes were early and late mortality and clinical complications. Endogenous von Willebrand Factor (vWF) antigen levels, vWF activity, and factor VIII levels were measured with admission labs and compared. Logistical regression was used to assess associations between mortality and blood type. RESULTS: Among 680 patients, 655 who had admission blood type data were included. 322 (49.2%) were type O, 186 (28.4%) were type A, 27 (4.1%) were type AB, and 120 (18.3%) were type B. The mean age, gender distribution, mechanism of injury, injury severity, and injury patterns were similar between blood types. There were significant racial and ethnic differences (P <
0.001 and P <
0.0018, respectively), and patients with endogenous type O blood had decreased levels of vWF activity and vWF antigen (P = 0.022 and P = 0.016, respectively). Logistical analyses showed no significant associations between blood type and complications, and type O blood was not associated with increased mortality. CONCLUSIONS: We found that endogenous blood type was not associated with increased mortality or clinical complications in severely injured patients requiring massive transfusion based on the data from a large multicenter trial.