The endogenous thrombin potential and the risk of venous thromboembolism

Background: The risk of venous thromboembolism (VTE) is increased by an excess of procoagulant or by a defect of anticoagulant proteins, with circumstantial risk factors playing a significant contribution. These conditions are directly linked to or are compatible with increased thrombin generation. Assuming that the more thrombin is generated the higher is the risk of VTE, an overall coagulation test monitoring ex vivo thrombin generation and reflecting the interaction of pro- and anticoagulant proteins would be useful to determine the risk of VTE. Patients and methods: This hypothesis was tested by measuring the endogenous thrombin potential (ETP) without or with thrombomodulin (TM) in plasmas from 403 individuals stratified according to their relative risk of VTE (no, low, intermediate, or high risk) according to whether or not they had congenital and/or circumstantial risk factors. Odds ratio (OR) and 95% confidence interval (CI), taken as a measure of the relative risk of having high levels of ETP, were calculated for the different categories relatively to the no-risk category. Results: When the ETP was measured with TM, ORs (95% CI) were 2.10 (1.23-3.60); 4.03 (2.18-7.45) and 4.96 (2.40-10.23) for the low-, intermediate and high-risk category. When ETP was measured without TM there was no gradient of OR values as function of the risk category. Conclusions: ETP measured with TM may help to distinguish individuals with different risk of VTE, however, the practical utility of measuring ETP in clinical practice remains to be evaluated in prospective studies.