Factor V Leiden carriers taking oral contraceptives have an increased risk of thrombosis

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I read with great interest the article, Factor V Leiden carriers taking oral contraceptives have an increased risk of thrombosis, published in the Journal this January, in which the authors discuss the risk of cardiovascular events in women taking combined oral contraceptives.1Beller J.P. McCartney C.R. Cardiovascular risk and combined oral contraceptives: clinical decisions in setting of uncertainty.Am J Obstet Gynecol. 2013; 208: 39-41Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar In effect, the use of oral contraceptives (OCs) has been associated with an increased risk of thrombosis.2Rosendaal F. Helmerhorst F. Vandernbrouke J. Female hormones and thrombosis.Arterioscler Thrombosis Vasc Biol. 2002; 22: 201-210Crossref PubMed Scopus (213) Google Scholar In the aforementioned Journal article,1Beller J.P. McCartney C.R. Cardiovascular risk and combined oral contraceptives: clinical decisions in setting of uncertainty.Am J Obstet Gynecol. 2013; 208: 39-41Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar the authors report some clinical circumstances that may increase this risk, among which they cite smoking in women 35 years old or older and women with a history of ischemic heart disease or stroke, hypertension, diabetes, and dyslipidemia.1Beller J.P. McCartney C.R. Cardiovascular risk and combined oral contraceptives: clinical decisions in setting of uncertainty.Am J Obstet Gynecol. 2013; 208: 39-41Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar It strikes us that among these risk factors the authors do not cite carriers of factor V Leiden because it is known that the presence of this thrombotic risk factor may increase the possibility of thrombotic events in women taking contraceptives.3Bloemenkamp K.W.M. Ronsendaal F.R. Helmerhorst F.M. et al.Enhancement by factor V Leiden mutation of risk of deep-vein thrombosis associated with oral contraceptives containing a third-generation progestagen.Lancet. 1995; 346: 1593-1596PubMed Scopus (618) Google Scholar Moreover, the prevalence of factor V Leiden in the European population is about 5%, ranging from 0.6% to 13.0%, and the prevalence of factor V Leiden carriers among white patients with deep venous thrombosis varies between 11.2% and 37.0%,4Aznar J. Vayá A. Estellés A. et al.Risk of venous thrombosis in carriers of the prothrombin G20210A variant and factor V Leiden and their interaction with oral contraceptives.Haematologica. 2000; 85: 1271-1276PubMed Google Scholar so the possibility of overlap between female factor V Leiden carriers and the intake of contraceptives could be common. For this reason, we have raised the question of whether it would be reasonable to perform screening for factor V Leiden before oral contraception.5Aznar J. Gilabert J. Oral contraceptive users and screening of Factor V Leiden.Thromb Haemost. 1999; 81: 845-846PubMed Google Scholar One of the arguments against screening for factor V Leiden to prevent secondary thrombotic events in women taking OCs is the economic cost. We evaluated this and concluded that screening for factor V Leiden may be recommended in women who are going to begin OC treatment if they have had previous thrombotic events or a family history of thrombosis.5Aznar J. Gilabert J. Oral contraceptive users and screening of Factor V Leiden.Thromb Haemost. 1999; 81: 845-846PubMed Google Scholar Cardiovascular risk and combined oral contraceptives: clinical decisions in settings of uncertaintyAmerican Journal of Obstetrics & GynecologyVol. 208Issue 1PreviewAlthough generally safe, combined oral contraceptives (COCs) are associated with risks, including an estimated 2-fold increased relative risk of cardiovascular events. For most women taking COCs for contraception, absolute cardiovascular risks are very low, and the overall risks of COCs are outweighed by the risks of unwanted pregnancy. Nonetheless, risks of COCs may be excessive in some women, and both the American College of Obstetricians (ACOG) and the World Health Organization (WHO) have offered contraindications for COC use. Full-Text PDF ReplyAmerican Journal of Obstetrics & GynecologyVol. 209Issue 2PreviewWe appreciate the interest that Drs Aznar and Cerdá have expressed in our Clinical Opinion piece. We did not intend to minimize the importance of factor V Leiden as a risk factor for venous thromboembolism (VTE) in women taking combined oral contraceptives (COCs). However, we primarily addressed the risks of myocardial infarction (MI) and ischemic stroke (IS), which are arterial thrombotic events, with COCs. Accordingly, we cited some well-established risk factors for MI and IS, and we suggested that tools such as the Framingham risk calculator may be helpful adjuncts to American College of Obstetricians and Gynecologists (ACOG) and World Health Organization (WHO) guidelines by allowing physicians to estimate the attributable risk of COC-related cardiovascular events such as MI and coronary death. Full-Text PDF