Risk of thrombosis associated with oral contraceptives of women from 97 families with inherited thrombophilia: high risk of thrombosis in carriers ofthe G20210A mutation of the prothrombin gene

Background and Objectives. Oral contraceptives (OC) and inherited thromboph ilia are well-known risk factors associated with venous thromboembolism (VT E). However, there are only few studies on the risk of WE in women with inh erited thrombophilia who use oral contraceptives. Design and Methods. We performed a retrospective family cohort study of 325 women belonging to 97 families with inherited thrombophilia, including ant ithrombin, protein S and C deficiencies, the factor V Leiden mutation (FVL) and the G20210A mutation of the prothrombin gene (PT20210A) to determine t he risk of WE associated with OC intake. Results. For carriers of the PT20210A mutation, the risk of VTE in OC users was 3-fold higher (95% CI 1.3-6.8) than that in non-carriers. Carriers of FVL mutation taking OC showed an OR of 1.4 (95% CI 0.6-3.3), indicating a t endency to increased risk of VTE. Interpretation and Conclusions. Because of the high prevalence of the PT202 10A (6.5%) and FVL (2%) mutations in the general Spanish population and the increased risk of VTE associated with OC intake, genetic screening for the se mutations should be considered in potential OC users belonging to famili es with thrombophilia. (C) 2001, Ferrata Storti Foundation.