Obesity is Associated with Postinjury Hypercoagulability


Obesity is linked to hypercoagulability with an increased risk of venous thromboembolic events (VTE) in the uninjured population. Therefore, we hypothesize that obesity (Body Mass Index (BMI) ≥30 kg/m) is associated with a hypercoagulable state postinjury characterized by increased clot strength and resistance to fibrinolysis.


Our prospective Trauma Activation Protocol database includes all trauma activations patients for whom a rapid thromboelastographic (TEG) is obtained within 60 minutes postinjury prior to any transfusions. The dataset was then stratified by BMI and subjects with BMI ≥ 30 kg/m were compared to those with BMI<30 kg/m). The following TEG measurements were obtained: activated clotting time (ACT), clot formation rate (angle), maximum clot strength (MA), and % clot lysis 30 min after MA (LY30, %). Fibrinolysis shutdown (SD) was defined as LY30 < 0.6% and hyperfibrinolysis (HF) as LY30 > 7.6%. Continuous variables are expressed as median (IQR).


Overall, 687 patients were included of whom 161 (23%) had BMI ≥ 30kg/m (BMI30). The BMI30 group was older, had a lower proportion of males and of blunt trauma, and were less severely injured. After adjustment for confounders, BMI30 was independently associated with lower odds of MA<55mm (OR 0.28; 95% CI 0.130.60) and of HF (OR 0.31; 95% CI 0.10- 0.97) and higher odds of SD (OR 1.82; 95% CI 1.09-3.05). No independent association was observed with angle<65 (OR 0.57 95% CI 0.30-1.05). While VTEs were more frequent among BMI30 patients (5.0 vs 3.3%), this did not reach significance after confounding adjustment (p=0.11).


Obesity was protective against diminished clot strength and hyperfibrinolysis, and obesity was associated with an increased risk of fibrinolytic shutdown in severely injured patients. These findings suggest a relative hypercoagulability. Although no difference in VTEs was noted in this study, these findings may explain the higher rate of VTEs reported in other studies.