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Variability in international normalized ratio and activated partial thromboplastin time after injury are not explained by coagulation factor deficits

Stettler, Gregory R. MD; Moore, Ernest E. MD; Moore, Hunter B. MD, PhD; Nunns, Geoffrey R. MD; Coleman, Julia R. MD, MPH; Colvis, Arthur; Ghasabyan, Arsen MPH; Cohen, Mitchell J. MD; Silliman, Christopher C. MD, PhD; Banerjee, Anirban PhD; Sauaia, Angela MD, PhD

Journal of Trauma and Acute Care Surgery: September 2019 - Volume 87 - Issue 3 - p 582–589
doi: 10.1097/TA.0000000000002385
ORIGINAL ARTICLES
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BACKGROUND Conventional coagulation assays (CCAs), prothrombin time (PT)/international normalized ratio (INR) and activated partial thromboplastin time (aPTT), detect clotting factor (CF) deficiencies in hematologic disorders. However, there is controversy about how these CCAs should be used to diagnose, treat, and monitor trauma-induced coagulopathy. Study objectives were to determine whether CCA abnormalities are reflective of deficiencies of coagulation factor activity in the setting of severe injury.

METHODS Patients without previous CF deficiency within a prospective database at an ACS-verified Level I trauma center had CF activity levels, PT/INR, aPTT, and fibrinogen levels measured upon emergency department arrival from 2014 to 2017. Linear regression assessed how CF activity explained the aPTT and PT/INR variation. Prolonged CCA values were set as INR greater than 1.3 and aPTT greater than 34 seconds. CF deficiency was defined as less than 30% activity, except for fibrinogen, defined as less than 150 mg/dL.

RESULTS Sixty patients with a mean age of 35.8 (SD, 13.6) years and median New Injury Severity Score of 32 (interquartile range, 12–43) were included; 53.3% sustained blunt injuries, 23.3% required massive transfusion, and mortality was 11.67%. Overall, 44.6% of the PT/INR variance and 49.5% of the aPTT variance remained unexplained by CF activity. Deficiencies of CFs were: common pathway, 25%; extrinsic pathway, 1.7%; and intrinsic pathway, 6.7%. The positive predictive value for CF deficiencies were: (1) PT/INR greater than 1.3:4.4% for extrinsic pathway, 56.5% for the common pathway; (2) aPTT greater than 34 seconds:16.7% for the intrinsic pathway, 73.7% for the common pathway.

CONCLUSION Almost half of the variances of PT/INR and aPTT were unexplained by CF activity. Prolonged PT/INR and aPTT were poor predictors of deficiencies in the intrinsic or extrinsic pathways; however, they were indicators of common pathway deficiencies.

LEVEL OF EVIDENCE Prognostic, level III.

From the Department of Surgery (G.R.S., E.E.M., H.B.M., G.R.N., J.R.C., A.C., M.J.C., C.C.S., A.B., A.S.), University of Colorado School of Medicine; Denver Health Medical Center (E.E.M., A.G., M.J.C.); Department of Pediatrics (C.C.S.), University of Colorado School of Medicine; Bonfils Blood Center (C.C.S.), and University of Colorado School of Public Health (A.S.). Denver, Colorado

Submitted: December 31, 2018, Revised: March 30, 2019, Accepted: April 3, 2019, Published online: May 24, 2019.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text, and links to the digital files are provided in the HTML text of this article on the journal’s Web site (www.jtrauma.com).

Address for reprints: Ernest E Moore, MD, 655 Bannock St, Denver, CO 80203; email: ernest.moore@dhha.org.

Online date: May 29, 2019

© 2019 Lippincott Williams & Wilkins, Inc.