The role of serum bilirubin levels in determining venous thromboembolism

Objective: Venous thromboembolism (VTE) is a disease that includes both deep venous thrombosis (DVT) and pulmonary embolism (PE). Bilirubin is an endogenous anti-inflammatory marker associated with atherothrombosis. The purpose of our study was to investigate the association of serum bilirubin levels with the presence of VTE. Methods: A total of 103 patients with VTE (distal DVT, n = 34; proximal DVT, n = 30; PE, n = 39) and 50 control patients were cross-sectionally enrolled. Peripheral venous duplex ultrasound and computed tomography were used for the diagnosis of VTE. Fasting blood samples were drawn for biochemical analyses. Results: Baseline characteristics were not different between groups. The VTE group had lower bilirubin level (9.0 +/- 2.6 mu mol/L vs 7.3 +/- 3 mu mol/L; P = .001) and higher high-sensitivity C-reactive protein (hs-CRP) concentration (0.8 [0.3-2] mg/L vs 1.1 [0.2-3] mg/L; P = .008) and white blood cell count (7.4 +/- 1.5 x 10(9)/L vs 8.2 +/- 2.7 x 10(9)/L; P = .02) compared with control patients. In the analysis of variance, the levels of total direct bilirubin and hs-CRP were clearly different between the control group and VTE subgroups (distal and proximal DVT and PE). The receiver operating characteristic curve analysis showed a cutoff value of 8.9 mu mol/L for total bilirubin (sensitivity, 74%; specificity, 55%) and an area under the curve of 0.659 (P < .001). Conclusions: Bilirubin level, hs-CRP concentration, and white blood cell count were independently associated with VTE.