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Is Low-Molecular Weight Heparin SAfe for Venous Thromboembolism Prophylaxis in Patients with Traumatic Brain Injury? A Western Trauma
Study Question: Can the safety of low-molecular-weight heparin (LMWH) for venous thromboembolism (VTE) prophylaxis in blunt intracranial injury be demonstrated?
Study Description: The Western Trauma Association (WTA) Multicenter Trials Committee conducted a multi-center, retrospective, cohort study which included patients who presented with intracranial hemorrhage caused by blunt injury. Patients with Abbreviated Injury Scale (AIS) score of ≥ 3, intracranial hemorrhage, blunt mechanism of injury, age > 18 years, head CT at admission, and at least one follow-up CT scan of the head were included. Patients with previous thromboembolic disease, on pre-injury anticoagulation with warfarin or therapeutic LMWH, on heparin for VTE prophylaxis, hospitalized < 48 hours, or required emergent thoracic, abdominal, or vascular surgery at admission were excluded. Patients were divided into two groups: those who received LMWH during their hospitalization (LMWH group) and those who did not (control group). The primary outcome measured was progression of intracranial hemorrhage documented by repeated head CT scan. Multivariate logistic regression analysis was performed to identify potential independent risk factors for intracranial hemorrhage progression.
Results: A total of 1,215 patients were included in the study. Of these, 220 patients (18.1%) received LMWH for VTE prophylaxis. The remaining 995 did not receive anticoagulants (81.9%) and served as the control group. Patients who received LMWH had more severe injury and lower GCS score at admission with a longer ICU and hospital length of stay. At presentation, patients in the LMWH group frequently required operation for their intracranial hemorrhages.
Ninety-three (42%) patients in the LMWH group were found to have progressive bleed on follow-up head CT scans. In the control group, 239 (24%) patients were found to have progression on follow-up CT scans (p<0.001). There was no difference in the rate of hemorrhage progression after receiving LMWH regardless of timing of LMWH initiation. Factors found to be independent risk factors for hemorrhage progression include age > 55 years, male sex, INR > 1.3, intra-axial hemorrhage, GCS < 9, and LMWH for deep vein thrombosis prophylaxis. LMWH was found to be the strongest risk factor for intracranial hemorrhage progression (OR 2.41; 95% CI 1.65-3.53). The LMWH group had 20 episodes of VTE while the control group had 31 episodes of VTE (9.1% vs. 3.1%, p<0.001). However, only 42% LMWH patients and 11% control patients had lower-extremity duplex ultrasounds.
Conclusion(s): Patients receiving LMWH were at higher risk for hemorrhage progression. LMWH was not demonstrated to be safe for VTE prophylaxis in patients with blunt traumatic brain injury. The risk of using LMWH may exceed its benefit.
Perspective: The use of LMWH for VTE prophylaxis in patients with blunt traumatic brain injury was not demonstrated to be safe according to the authors of this study. Nevertheless, the results of this study should be interpreted with caution. There was variability observed among the participating centers with respect to use of LMWH. Additionally, the baseline characteristics between the LMWH and control groups were significantly different in that the LMWH group was more injured and more likely to require neurosurgical intervention in the first 24 hours. The indications and timing for performing repeated head CT scans for evaluation of progression were variable among the participating centers. The retrospective design of this study precludes making any definitive conclusions regarding the safety of VTE prophylaxis in patients with blunt traumatic brain injury.