Acquired Risk Factors Play a Major Role in Venous Thrombosis in Chinese Population.

Acquired and genetic risk factors are associated with the occurrence of venous thrombotic embolism (VTE). In the Western population, 30 to 50% of the patients suffering from VTE are due to a genetic tendency to thrombosis. However, some common thrombotic risk factors in thrombophilia such as the factor V Leiden and the G20210A mutation of prothrombin are very rare in China and other Asiatic countries. Recently, we prospectively investigated the incidence of VTE among 768 hospitalized patients who had at least one of acquired risk factors such as prolonged immobilization, surgery, fracture, pregnancy, post-partum, cancer, diabetes mellitus, and some autoimmune diseases. The clinical VTE diagnosis was confirmed with Doppler ultrasonography, CT or/and venography. 17 patients (2.2%) developed VTE with one being complicated with pulmonary thromboembolism during their hospitalization. 90% of these cases had proximal deep vein thrombosis. It is notable that a high incidence of VTE (13.04%) has been found in patients in the intensive care unit, associated with many medical conditions including severe diseases, long lying in bed, multi-organ failure, infection and hypercoagulability. All these 17 VTE patients were extensively studied to identify and characterize the genetic anomalies predisposing possibly to thrombosis. Two were found to be of inherited antithrombin deficiency, and one of inherited protein C deficiency. Each of the three patients had the characteristics of recurrent VTE and/or familial history of VTE with episodes recognized at least in 2 family members. Our results suggest there might be a great variation according to the geographic origin of the population. The acquired risk factors play a much more important role than genetic risk factors in occurrence of VTE in Chinese population in comparison with Caucasians.