High plasma levels of factor VIII: an important risk factor for isolated pulmonary embolism

OBJECTIVE: The aim of the study was to investigate whether factor V Leiden and prothrombin G20210A mutations, elevated levels of factor VIII and factor IX are associated with pulmonary embolism (PE). METHODS: Sixty-four patients with objectively documented PE and 64 control subjects were included in this study. The authors divided the 64 subjects with PE into those with PE and deep vein thrombosis (combined form of venous thromboembolism, n = 26) and those with PE without deep vein thrombosis (isolated PE n = 38). RESULTS: There was no significant difference between the PE groups and the control subjects with regard to the presence of factor V Leiden and prothrombin mutations and elevated levels of factor IX. Using the 90th percentile measured in control subjects (P(90) = 168 U/dL) as a cut-off point for factor VIII levels, the authors found an 11-fold increased risk for both isolated PE patients and patients with a combined form of venous thromboembolism who have factor VIII levels >168 U/dL compared with individuals having factor VIII levels below this cut-off point. The risk was not affected by adjustments for other possible risk factors. CONCLUSIONS: Elevated plasma factor VIII levels were found to be a significant, independent risk factor for PE.