Early venous thromboembolic event prophylaxis in traumatic brain injury with low-molecular-weight heparin: risks and benefits.

Traumatic brain injury (TBI) patients are known to be at high risk for venous thromboembolic events (VTEs). The Brain Trauma Foundation Guidelines (2007) state that low-molecular-weight heparin or unfractionated heparin should be used to prevent VTE complications, but suggest that there is an increased risk of expansion of intracranial hemorrhages (ICH) with VTE prophylaxis. In addition, it is unclear which treatment regimen (i.e., medication, dose, and timing) provides the best risk:benefit ratio in TBI patients. We reviewed all moderate-to-severe TBI patients admitted over a 5-year period to: (1) examine the occurrence of VTEs and their timing; (2) examine the symptomatic expansion of ICH while on VTE prophylaxis; and (3) compare the efficacy of two prophylactic agents: enoxaparin and dalteparin. Two-hundred eighty-seven patients were included. VTE prophylaxis was started 48-72 h post-trauma in all individuals who had no confounding coagulopathy, when two consecutive computed tomography (CT) scans revealed hemorrhage stability. VTEs occurred in 7.3% of treated patients, mostly within 2 weeks after trauma. Proximal VTEs occurred in 3.1% of treated patients. No significant difference in VTE rates was seen between enoxaparin (7.0%) and dalteparin (7.5%; p = 0.868). Moreover, the group treated with dalteparin was more severely injured (higher Injury Severity Score [p = 0.002]), had lower Glasgow Coma Scale (GCS) scores (p = 0.003), and had more inferior vena cava (IVC) filters placed (p = 0.007). The two groups did not show significant differences in the development of VTE when controlled for ISS and IVC filters (p = 0.819). Importantly, only one patient suffered a symptomatic expansion of ICH while on VTE prophylaxis, at 15 days post-trauma. These results suggest that current regimens of VTE prophylaxis used in our TBI population provide a relatively high level of protection against VTEs, and an extremely low risk of expanding ICH. They also suggest that there was no difference in VTE between dalteparin- and enoxaparin-treated patients.