Does traumatic brain injury increase the risk for venous thromboembolism in polytrauma patients?

BACKGROUND: Trauma is a major risk factor for venous thromboembolism (VTE). Traumatic brain injury (TBI) is generally considered to further increase the VTE risk, which should prompt routine thromboprophylaxis. However, the associated risk for intracranial hemorrhage often delays anticoagulants. We test the hypothesis that TBI associated with polytrauma results in a higher rate of VTE than polytrauma without TBI. METHODS: From August 2011 to June 2013, a prospective observational trial with informed consent was performed in 148 intensive care unit (ICU) patients with a Greenfield Risk Assessment Profile score of 10 or greater. RESULTS: Demographics, Greenfield Risk Assessment Profile scores, the incidence of polytrauma, and mortality were similar, but TBI patients had worse Injury Severity Scores (ISS) (32 vs. 22), longer ICU lengths of stay (21 days vs. 12 days), more hypercoagulable thromboelastogram values on admission (94% vs. 79%), more received unfractionated heparin prophylaxis (65% vs. 36%), and the prophylaxis start date was more than a day later (all p < 0.05). Nevertheless, the VTE rate with TBI was similar to that without TBI (25% vs. 26%, p = 0.507). Furthermore, VTE occurred at similar time points after ICU admission with and without TBI. In both groups, about 30% of the VTEs were detected within 2 days of ICU admission and 50% of the VTEs occurred within 10 days of admission despite chemical and mechanical thromboprophylaxis. CONCLUSION: In complex polytrauma patients who survived to ICU admission and who were prescreened for high VTE risk, TBI did not further increase the risk for VTE. The most likely explanation is that no single risk factor is necessary or sufficient for VTE development, especially in those who routinely receive chemical and mechanical thromboprophylaxis. LEVEL OF EVIDENCE: Epidemiologic study, level III.