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Original Investigation
Pacific Coast Surgical Association
October 19, 2016

Thrombelastography-Based Dosing of Enoxaparin for Thromboprophylaxis in Trauma and Surgical PatientsA Randomized Clinical Trial

Author Affiliations
  • 1Division of Trauma, Critical Care, and Acute Care Surgery, Department of Surgery, Oregon Health and Science University, Portland
  • 2Department of Surgery, Oregon Health and Science University, Portland
  • 3Department of Surgery, University of Washington, Seattle
  • 4Harborview Medical Center, University of Washington, Seattle
  • 5Harborview Injury Prevention and Research Center, University of Washington, Seattle
  • 6Center for Translational Injury Research, Division of Acute Care Surgery, Department of Surgery, The University of Texas Medical School, Houston
JAMA Surg. 2016;151(10):e162069. doi:10.1001/jamasurg.2016.2069
Key Points

Question  Is thrombelastogram-adjusted enoxaparin better than standard-dose enoxaparin in the prevention of venous thromboembolism?

Findings  In this randomized clinical trial that included 185 trauma and surgical patients, patients receiving thrombelastogram-adjusted doses received a higher median enoxaparin dose than control group patients. Venous thromboembolism rates were similar.

Meaning  Venous thromboembolism incidence was low and was similar between the groups receiving thrombelastogram-adjusted and standard enoxaparin dosing in this study population.


Importance  Prophylactic enoxaparin is used to prevent venous thromboembolism (VTE) in surgical and trauma patients. However, VTE remains an important source of morbidity and mortality, potentially exacerbated by antithrombin III or anti–Factor Xa deficiencies and missed enoxaparin doses. Recent data suggest that a difference in reaction time (time to initial fibrin formation) greater than 1 minute between heparinase and standard thrombelastogram (TEG) is associated with a decreased risk of VTE.

Objective  To evaluate the effectiveness of TEG-adjusted prophylactic enoxaparin dosing among trauma and surgical patients.

Design, Setting, and Participants  This randomized clinical trial, conducted from October 2012 to May 2015, compared standard dosing (30 mg twice daily) with TEG-adjusted enoxaparin dosing (35 mg twice daily) for 185 surgical and trauma patients screened for VTE at 3 level I trauma centers in the United States.

Main Outcomes and Measures  The incidence of VTE, bleeding complications, anti–Factor Xa deficiency, and antithrombin III deficiency.

Results  Of the 185 trial participants, 89 were randomized to the control group (median age, 44.0 years; 55.1% male) and 96 to the intervention group (median age, 48.5 years; 74.0% male). Patients in the intervention group received a higher median enoxaparin dose than control patients (35 mg vs 30 mg twice daily; P < .001). Anti–Factor Xa levels in intervention patients were not higher than levels in control patients until day 6 (0.4 U/mL vs 0.21 U/mL; P < .001). Only 22 patients (11.9%) achieved a difference in reaction time greater than 1 minute, which was similar between the control and intervention groups (10.4% vs 13.5%; P = .68). The time to enoxaparin initiation was similar between the control and intervention groups (median [range] days, 1.0 [0.0-2.0] vs 1.0 [1.0-2.0]; P = .39), and the number of patients who missed at least 1 dose was also similar (43 [48.3%] vs 54 [56.3%]; P = .30). Rates of VTE (6 [6.7%] vs 6 [6.3%]; P > .99) were similar, but the difference in bleeding complications (5 [5.6%] vs 13 [13.5%]; P = .08) was not statistically significant. Antithrombin III and anti–Factor Xa deficiencies and hypercoagulable TEG parameters, including elevated coagulation index (>3), maximum amplitude (>74 mm), and G value (>12.4 dynes/cm2), were prevalent in both groups. Identified risk factors for VTE included older age (61.0 years vs 46.0 years; P = .04), higher body mass index (calculated as weight in kilograms divided by height in meters squared; 30.6 vs 27.1; P = .03), increased Acute Physiology and Chronic Health Evaluation II score (8.5 vs 7.0; P = .03), and increased percentage of missed doses per patient (14.8% vs 2.5%; P = .05).

Conclusions and Relevance  The incidence of VTE was low and similar between groups; however, few patients achieved a difference in reaction time greater than 1 minute. Antithrombin III deficiencies and hypercoagulable TEG parameters were prevalent among patients with VTE. Low VTE incidence may be due to an early time to enoxaparin initiation and an overall healthier and less severely injured study population than previously reported.

Trial Registration  clinicaltrials.gov Identifier: NCT00990236.