Associations between coagulation factor XII, coagulation factor XI, and stability of venous thromboembolism: A case-control study

BACKGROUND: Pulmonary embolism (PE) is a fatal clinical syndrome that is generally caused by an embolus from unstable deep venous thrombosis (DVT). However, clinical and biochemical factors that are related to the stability of DVT are not fully understood. AIM: To evaluate the relationships between plasma antigen levels of factor XII (FXII:Ag) and factor XI (FXI:Ag) with the stability of DVT. METHODS: Patients with DVT and no PE, DVT and PE, and controls with no DVT or PE that matched for age, gender, and comorbidities were included in this study. FXII:Ag and FXI:Ag in peripheral venous blood were measured using enzyme-linked immunosorbent assays. RESULTS: Using the 95(th) percentile of FXI:Ag in patients with DVT and PE as the cut-off, a higher FXI:Ag was associated with a higher risk of unstable DVT (odds ratio: 3.15, 95% confidence interval: 1.18-8.43, P = 0.019). Stratified analyses showed consistent results in patients ≤ 60 years (P = 0.020), but not in those > 60 years (P = 0.346). CONCLUSION: Higher plasma FXI:Ag might be a marker for unstable DVT, which might be associated with PE in these patients.