Background: To address deficiencies associated with the classic definition of massive transfusion (MT), critical administration threshold (CAT) and resuscitation intensity (RI) were developed to better quantify the overall severity of illness and predict the need for transfusions and early mortality. We sought to evaluate these as more appropriate replacements for MT in defining mortality risk in patients undergoing major transfusions.
Methods: Patients predicted to receive MT at 12 Level I trauma centers were randomized in the Pragmatic, Randomized Optimal Platelet and Plasma Ratios (PROPPR) trial. MT of 10 U or greater red blood cell (RBC) in 24 hours; CAT+, 3 U or greater RBC in the first hour; and RI, total products in the first 30 minutes (1 U RBC, 1 U plasma, 1000 mL crystalloid, 500 mL colloid each valued at 1 U). Resuscitation intensity was evaluated as a continuous variable and dichotomized as RI4+, where RI is 4 U or greater. Each metric was evaluated for its ability to predict mortality at 3 hours, 6 hours, and 24 hours, and at 30 days.
Results: Of the 680 patients, 301 patients met MT definition, 521 were CAT+, and 445 were RI4+. Of those that died, 23% never reached MT threshold, but all were captured by CAT+ and RI4+. The 3-hour (9% vs. 9%), 6-hour (14% vs. 14%), 24-hour (17% vs. 18%), and 30-day mortality rates (28% vs. 29%) were similar between CAT+ and RI4+ patients. When RI was evaluated as a continuous variable, each unit increase was associated with a 20% increase in hemorrhage-related mortality (odds ratio, 1.20; 95% confidence interval, 1.15-1.29; p < 0.05).
Conclusion: Both RI and CAT are valid surrogates for early mortality in patients undergoing major transfusion, capturing patients omitted by the MT definition. The CAT+ showed the best sensitivity; RI4+ demonstrated better specificity and good positive predictive values and negative predictive values. While CAT+ may be suited for patients receiving an RBC-dominant resuscitation, RI4+ is more comprehensive. RI can also be used as a continuous variable to provide quantitative as well as qualitative risk of death.
Level of evidence: Prognostic, level III.