Background: Venous thromboembolism, including deep vein thrombosis (DVT) and pulmonary embolism (PE), are common life-threatening complications of severe traumatic brain injury (TBI). Despite the potential for venous thromboembolism chemoprophylaxis treatment (VTC) to reduce the risk of these complications and improve outcomes, use of this treatment in patients with TBI remains controversial. Our previous study of military patients with severe TBI in Iraq and Afghanistan showed potential for benefit from use of VTC. However, a larger study is needed to confirm this conclusion.

Objective/Hypotheses: In patients with severe closed and penetrating brain injury sustained in the wars in Iraq and Afghanistan, we hypothesize that early administration of VTC within <48 hours of sustaining a severe TBI will be associated with improved outcomes.

Specific Aims:

Specific Aim 1: Create a Comprehensive TBI Database.

Specific Aim 2: Abstract Data into the Database.

Specific Aim 3: Analyze the Data. (1) Describe the clinical course of US military personnel with severe TBIs sustained in combat. (2) Describe the demographic and injury characteristics. (3) Describe the prevalence of early use of VTC and procoagulant medications (Factor VII, Tranexamic Acid). (4) Calculate the incidence of adverse outcomes (worsening intracranial hemorrhage, DVT, PE, mortality) by type and severity of TBI (moderate/severe closed, penetrating). (5) Calculate the unadjusted and adjusted hazard ratios (risk estimates) for adverse outcomes associated with early use of VTC.

Study Design: This retrospective cohort study will use the Department of Defense Trauma Registry (DoDTR) to identify US military with severe closed and penetrating TBIs sustained in Iraq and Afghanistan from 2001 through the most recent data available in 2016. Detailed clinically relevant TBI data will be abstracted and entered into the DoDTR TBI Module database. Existing data from the DoDTR and from the TBI module will then be analyzed. The distribution of characteristics of patients who did and did not receive early VTC will be calculated using descriptive statistics. Risk estimates for adverse outcomes for patients who were given early VTC vs. those who were not will be calculated using Cox Proportional Hazards methods.

Relevance: Despite the association of TBI with DVT and PE, relatively few rigorous studies on this topic have been published. The longstanding fear that using VTC will cause an increase in the size of intracranial hemorrhage has contributed to the paucity of studies in this area. Clinical practice has therefore largely been guided by a few Class III studies and occasional updates in expert opinion. Our study will provide further evidence regarding the potential for VTC to inform official DoD Clinical Practice Guidelines for care of wounded Service personnel in theater and improve outcomes for both military and civilian patients with TBI.