Clinical characteristics of patients with factor V Leiden or prothrombin G20210A and a first episode of venous thromboembolism. Findings from the RIETE Registry

Abstract Background The clinical characteristics of patients with factor V Leiden or prothrombin G20210A presenting with a first episode of venous thromboembolism (VTE) have not been thoroughly studied. Methods RIETE is an ongoing registry of consecutive patients with acute VTE. We compared the clinical characteristics of patients with factor V Leiden, prothrombin G20210A, or no thrombophilia, at presentation with a first episode of VTE. Results As of May 2009, 22428 patients had been enrolled with a first episode of VTE. Of these, 345 had factor V Leiden, 261 had prothrombin G20210A, and 2399 tested negative. Sixty-two percent of the VTE episodes in women with factor V Leiden or prothrombin G20210A (40% in men) were associated with an acquired risk factor. Among women, pregnancy or contraceptive use accounted for 63% and 67% of such risk factors. Patients with factor V Leiden presented with pulmonary embolism (PE) less likely than those with prothrombin G20210A (31% vs. 51%; p < 0.001) or with negative testing (31% vs. 45%, p < 0.001). In addition, PE patients with Factor V Leiden presented with hypoxaemia (Sat O2 levels < 90%) less likely than those with prothrombin G20210A (4.5% vs. 17%; p < 0.001) or with no thrombophilia (4.5% vs. 20%; p < 0.001). Conclusions Most VTE episodes in women (not men) with factor V Leiden or prothrombin G20210A were associated with an acquired risk factor (mostly pregnancy or contraceptive use). Only 4.5% of patients with factor V Leiden presenting with acute PE had hypoxaemia.