Whole Blood Not Better Than Components En Route to Hospital After Traumatic Injury

For patients at risk of hemorrhagic shock after a traumatic injury, transfusing whole, type O blood rather than blood components on the way to the hospital yielded similar outcomes, the randomized TOWAR trial showed.

Thirty-day mortality came out at 25.9% in whole-blood recipients and 20.5% in those who got component transfusions (adjusted OR 1.24, 95% CI 0.87-1.76, P=0.24), reported Jason L. Sperry, MD, MPH, of the University of Pittsburgh (Pitt), at the American Thoracic Society annual meeting in Orlando. The findings were published simultaneously in the New England Journal of Medicine.

An observational substudy to examine the impact of how old the whole blood was likewise indicated no significant difference in 30-day mortality whether 15-21 or 1-14 days after donation (27.1% vs 26.4%, adjusted OR 0.99, 95% CI 0.74-1.32).

“This is good news,” said co-author Francis X. Guyette, MD, MPH, also of Pitt, and medical director of STAT MedEvac. “It means that emergency responders can use whatever form of blood is most accessible to them,” he said in a statement. “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.”

The findings follow on the heels of the SWIFT trial from England that also showed similar impact from whole blood versus blood components, with guideline changes predicted.

Whole blood is increasingly used in prehospital military and civilian settings, with the thought that it might yield better results due to balanced volume resuscitation and concomitant reversal of coagulopathy along with simpler logistics and long shelf life, the researchers noted.

Thus, the phase III TOWAR trial was designed to find superiority. It cluster-randomized 44 air medical bases in a 2:1 ratio to the open-label use of up to 2 units of whole blood or indicated blood components (plasma, red cells, or both) for prehospital transfusion in trauma patients during 1-month blocks, with a total of 1,020 patients transported to hospitals by those bases during the study period.

Most of the patients were men (73.5%), the median Injury Severity Score was 25 (scale ranges from 1-75, with a score >15 indicating major trauma), and 70.8% were transported from the scene of injury.

Secondary outcomes were similar between groups, including units of blood products transfused within 24 hours after arrival at the hospital, multiple organ failure, nosocomial infection, acute respiratory distress syndrome, coagulation measurements, and platelet function measurements. Adverse events (AEs), including serious AEs, also didn’t differ significantly between groups in the primary analysis or when stratified according to the storage age of whole blood in the observational substudy.

Study limitations included potential risk of type II error due to several factors: Blood product crossover between trial groups occurred not infrequently, with 31.6% of the whole-blood group receiving blood components, either alone or in addition to whole blood, and, in the component-randomized group, 4.9% received 1 unit of whole blood and 3.6% received 2 units of whole blood. Also, patients could have gotten transfusions before randomization, and transfusion volume was higher once at the hospital than en route.