Giving whole blood or the component parts of blood are equally effective options for paramedics and emergency medical technicians to use in treating patients with severe, traumatic bleeding before arriving at the hospital, according to a large, nationwide trial directed by University of Pittsburgh and UPMC clinicians and scientists.
The results, published today in the New England Journal of Medicine and simultaneously presented at the American Thoracic Society 's annual meeting in Orlando, provide flexibility to prehospital emergency care providers and could increase the odds that traumatically injured patients receive blood as soon as possible.
"Traumatic bleeding is the leading cause of trauma death and is the most time-sensitive injury a person could suffer – more time sensitive than a stroke or heart attack," said co-lead author Jason Sperry, M.D., M.P.H., chief of trauma surgery at UPMC and Andrew B. Peitzman Professor of Surgery in Pitt's School of Medicine . "But it is preventable – and that starts with giving blood back to the injured person before they even arrive at the hospital."
Donated blood is usually separated into parts – red cells, plasma and platelets – for storage and so the parts can be used individually as needed. When someone is bleeding, they're losing all these parts, so emergency clinicians will often give all or some of these parts to that patient at once. Giving either whole blood or its component parts had long been considered a safe option.
But which is better for treating severe bleeding: Giving never-separated whole blood or giving the components? The answer matters for blood bank and emergency care logistics.
Sperry and fellow principal investigators Francis Guyette, M.D., M.S., M.P.H., professor of emergency medicine in Pitt's School of Medicine , and Stephen Wisniewski, Ph.D., professor of epidemiology and associate vice chancellor for clinical trials coordination at Pitt, launched the Type O Whole blood and assessment of Age during prehospital Resuscitation (TOWAR) Trial to find out.
The multi-center trial, which ran from May 2022 to June 2025, enrolled and included 1,020 severely bleeding patients who were transferred to a trauma center by medical helicopter. The patients were randomized 2-to-1 to receive either whole blood or blood components.
The research team found no statistically significant difference between the two study arms. In both cases about a fifth to a quarter of the patients died within 30 days, compared to a third of traumatically bleeding patients who do not receive blood before arriving at the hospital.
"This is good news," said co-lead author Guyette, who is also medical director of STAT MedEvac , which is directed by a consortium of UPMC hospitals and is the nation's largest academic, nonprofit critical care transport group. "It means that emergency responders can use whatever form of blood is most accessible to them. In U.S. civilian emergencies, that may be component blood because that is how most blood banks package it, but in military settings whole blood is often all that is available. We've shown that both are equally great options."
In March, a European group announced the results of a similar, slightly smaller trial conducted in England, also published in the New England Journal of Medicine . Like the Pittsburgh team, they also found that giving whole blood or blood components was equally effective. The clinician-researchers believe that the combined findings will be reflected in guidelines set by various societies that oversee trauma care, surgery and blood handling.
Whole blood is good for 21 days after donation, so the clinician-scientists were also curious if patient outcomes were any different if they were given new blood or blood closer to the expiration date. They learned that it made no difference – outcomes were the same for patients receiving newer blood within 14 days of donation compared to those receiving older blood within seven days of expiration.
"Our thoughtful approach to the study design allowed us to not only answer the important question of the efficacy of whole blood compared to component therapy, but also to evaluate the health impact of an important public health question, the age of whole blood," said senior author Wisniewski, who is also co-director of the Epidemiology Data Center at Pitt's School of Public Health . "Our trial provides reassurance by verifying current standards that support the use of whole blood units throughout their entire shelf life."
The team also noted that the findings wouldn't have been possible without the generosity of blood donors, study participants agreeing to share their data and the hard work of emergency care providers.
"We're very grateful to everyone involved, particularly the paramedics, emergency medical technicians and flight nurses," Guyette said. "We are hopeful that this study and future research will give them better tools to save lives."
Additional authors from Pitt, UPMC or both are James F. Luther, M.A., Matthew D. Neal, M.D., Mark H. Yazer, M.D., Christian Martin-Gill, M.D., Laura E. Vincent, M.S., R.N., Ashley Harner, B.S., and Bedda Rosario-Rivera, Ph.D. Other authors listed on the manuscript are from the U niversity of Texas Health Science Center at Houston , University of Washington , University of Mississippi Medical Center , University of Cincinnati , MetroHealth Medical Center , University of Louisville , University of Alabama at Birmingham Health System , University of Manitoba and University of Tennessee Knoxville .
This research was supported by the Congressionally Directed Medical Research Program and the U.S. Army Medical Research Acquisition Activity under contract no. W81XWH-16-D-0024, task order W81XWH-20-F-0383 and R35GM119526.
