Body Mass Index and Pharmacologic Venous Thromboembolism Prophylaxis in Traumatic Brain Injury

Patients with traumatic brain injury (TBI) are at risk for developing venous thromboembolic complications. Previous work suggests venous thromboembolism (VTE) prophylaxis with low molecular weight heparin (LMWH) is protective compared to unfractionated heparin (UH) in trauma patients. The purpose of this study was to evaluate the role of body mass index (BMI) and type of pharmacological VTE prophylaxis in patients who develop VTE with severe TBI.

Patients with a severe TBI who received VTE prophylaxis were queried from the 2019 American College of Surgeons Trauma Quality Improvement Program database. Demographics, injury characteristics, timing of VTE prophylaxis, and BMI were collected. Outcome measures include VTE, mortality, and neurosurgical interventions.

Of the 39,520 patients with severe TBI included in the study, 25,671 received LMWH and 13,849 received UH. Multivariable logistic regression found patients with a BMI 25-29.9 kg/m² (odds ratio [OR] 1.375; 95% confidence interval [CI] 1.180-1.603; P < 0.0001) and a BMI>30 kg/m² (OR 1.831; 95% CI 1.570-2.137; P < 0.0001) were independent predictors of VTE. Patients with BMI of 25-29.9 kg/m² (OR 1.145; 95% CI 1.016-1.289; P = 0.0265) have a higher risk of mortality. For every hour delay in initiation to VTE prophylaxis, patients were 0.2% more likely to develop VTE (OR 1.002; 95% CI 1.002-1.003; P < 0.0001). Patients treated with UH were more likely to develop VTE complications (OR 1.085; 95% CI 1.058-1.112; P < 0.0001) and have increased mortality (OR 1.116; 95% CI 1.094-1.139; P < 0.0001), regardless of BMI and time to initiation of prophylaxis, compared to patients treated with LMWH.

In patients with severe TBI, higher BMI was associated with an increased risk of VTE and death. Delay in VTE prophylaxis initiation was associated with an increased risk of VTE. LMWH had a protective association with VTE.