PROJECT SUMMARY In collaboration with the University of Alabama (UAB), we propose to conduct the five-year, “Trauma Resuscitation with Group O Whole Blood Or Products” (TROOP) trial, a pragmatic, multicenter, phase III randomized clinical trial to evaluate the clinical effectiveness and safety of whole blood, compared with component blood therapy in trauma patients predicted to require large volume blood transfusions. The primary hypothesis of the TROOP trial is that the group treated with whole blood will exhibit no worse mortality and/or lower mortality compared to component therapy at 6 hours. The rationale for this trial is that although the current standard of care in trauma transfusion is the balanced administration of equal numbers of units of blood components (packed red blood cells, plasma, and platelets), 123 U.S. trauma centers currently use LTOWB for trauma resuscitation. Thus, a renewed approach to blood transfusion therapy in trauma is to use whole blood from the outset. Compared with component therapy, transfusion with whole blood offers several logistical and potentially clinical advantages; however, there are only a small number of observational studies that have compared the strategies. The specific aims of the TROOP trial clinical coordinating center (CCC) application submitted by UAB are to: (1) determine the effectiveness of whole blood versus component therapy at 6 hours in critically injured patients; and 2) evaluate the safety of whole blood compared to component therapy by evaluating longer term endpoints: 24 hours, 30 days, and major complications. To assess these specific aims, the trial uses a highly innovative, Bayesian, group-sequential, combined non- inferiority/superiority design, and pre-planned cost-effectiveness analysis. The trial has been designed in collaboration with NHLBI’s Innovative Clinical Trials Resource, funded by a U34 Planning Grant (U34HL148472). The accompanying CCC application from UAB describes the details of the clinical background and rationale for the study, eligibility criteria, treatment and follow-up procedures, and the organizational structure of TROOP. The Coordinating Center for Clinical Trials in the Department of Biostatistics and Data Science at the University of Texas Health Science Center at Houston will serve as the statistical and data coordination center (DCC) for the TROOP Trial. This DCC application describes the TROOP trial aims, expertise of the DCC, its role in the TROOP trial, details of data processing and management, and details of the Bayesian statistical design, analysis plan, and potential pitfalls.