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Recursive partitioning identifies greater than 4 U of packed red blood cells per hour as an improved massive transfusion definition

Moren, Alexis Marika MD, MPH; Hamptom, David MD, MEng; Diggs, Brian PhD; Kiraly, Laszlo MD; Fox, Erin E. PhD; Holcomb, John B. MD; Rahbar, Mohammad Hossein PhD; Brasel, Karen J. MD, MPH; Cohen, Mitchell Jay MD; Bulger, Eileen M. MD; Schreiber, Martin A. MDon behalf of the PROMMTT Study Group

Journal of Trauma and Acute Care Surgery: December 2015 - Volume 79 - Issue 6 - p 920–924
doi: 10.1097/TA.0000000000000830
WTA Plenary Papers
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BACKGROUND Massive transfusion (MT) is classically defined as greater than 10 U of packed red blood cells (PRBCs) in 24 hours. This fails to capture the most severely injured patients. Extending the previous work of Savage and Rahbar, a rolling hourly rate-based definition of MT may more accurately define critically injured patients requiring early, aggressive resuscitation.

METHODS The Prospective Observational Multicenter Major Trauma Transfusion (PROMMTT) trial collected data from 10 Level 1 trauma centers. Patients were placed into rate-based transfusion groups by maximal number of PRBCs transfused in any hour within the first 6 hours. A nonparametric analysis using classification trees partitioned data according to mortality at 24 hours using a predictor variable of maximum number PRBC units transfused in an hour. Dichotomous variables significant in previous scores and models as predictors of MT were used to identify critically ill patients: a positive finding on Focused Assessment with Sonography in Trauma (FAST) examination, Glasgow Coma Scale (GCS) score less than 8, heart rate greater than 120 beats/min, systolic blood pressure less than 90 mm Hg, penetrating mechanism of injury, international normalized ratio greater than 1.5, hemoglobin less than 11, and base deficit greater than 5. These critical indicators were then compared among the nodes of the classification tree. Patients omitted included those who did not receive PRBCs (n = 24) and those who did not have all eight critical indicators reported (n = 449).

RESULTS In a population of 1,245 patients, the classification tree included 772 patients. Analysis by recursive partitioning showed increased mortality among patients receiving greater than 13 U/h (73.9%, p < 0.01). In those patients receiving less than or equal to 13 U/h, mortality was greater in patients who received more than 4 U/h (16.7% vs. 6.0%, p < 0.01) (Fig. 1). Nodal analysis showed that the median number of critical indicators for each node was 3 (2–4) (≤4 U/h), 4 (3–5) (>4 U/h and ≤13 U/h), and 5 (4–5.5) (>13 U/h).

CONCLUSION A rate-based transfusion definition identifies a difference in mortality in patients who receive greater than 4 U/h of PRBCs. Redefining MT to greater than 4 U/h allows early identification of patients with a significant mortality risk who may be missed by the current definition.

LEVEL OF EVIDENCE Prognostic/epidemiologic study, level III.

From the Division of Trauma, Critical Care and Acute Care Surgery (A.M.M., D.H., B.D., L.K., K.J.B., M.A.S.), School of Medicine, Oregon Health & Science University, Portland, Oregon; Center for Translational Injury Research (E.E.F., J.B.H.), Division of Acute Care Surgery, Department of Surgery, Medical School, University of Texas Health Science Center, Houston, Texas; Biostatistics/Epidemiology/Research Design Core (M.H.R.), Center for Clinical and Translational Sciences, University of Texas Health Science Center, Houston, Texas; Division of General Surgery (M.J.C.), Department of Surgery, School of Medicine, University of California San Francisco, San Francisco, California; Division of Trauma and Critical Care (E.M.B.), Department of Surgery, School of Medicine, University of Washington, Seattle, Washington.

Submitted: January 9, 2015, Revised: June 26, 2015, Accepted: July 2, 2015, Published online: October 1, 2015.

*PROMMTT Study Group participants are listed in the Appendix.

This study was presented at the 45th annual meeting of the Western Trauma Association, March 1–6, 2015, in Telluride, Colorado. Portions of this article were presented as a poster at the Military Health System Research Symposium, August 19, 2014, in Fort Lauderdale, Florida.

Address for reprints: Alexis Moren, MD, 3181 SW Sam Jackson Park Rd, Portland, OR 97239; email: moren@ohsu.edu.

© 2015 Lippincott Williams & Wilkins, Inc.