Sex may matter when it comes to the presenting location of deep vein thrombosis

The incidence, risk factors, clinical presentation, and prognosis of cardiovascular diseases differ among men and women [ [1] Pilote L. et al. A comprehensive view of sex-specific issues related to cardiovascular disease. CMAJ. 2007; 176: S1-44 Crossref PubMed Scopus (320) Google Scholar , [2] Tan Y.C. et al. Gender differences in outcomes in patients with acute coronary syndrome in the current era: a review. Eur. Heart J. Acute Cardiovasc. Care. 2016; 5: 51-60 Crossref PubMed Scopus (28) Google Scholar ]. Defining, measuring, understanding and responding to these differences is important in an era of individualized and precision medicine. Sex specific differences in the incidence of venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), have long been recognized. Women are at higher risk during fertile years, mainly due to the effects of pregnancy and oral contraceptive use [ [3] Bleker S.M. Coppens M. Middeldorp S. Sex, thrombosis and inherited thrombophilia. Blood Rev. 2014; 28: 123-133 Crossref PubMed Scopus (38) Google Scholar ], and men are at higher risk at older ages [ [4] Roach R.E. et al. Sex difference in risk of second but not of first venous thrombosis: paradox explained. Circulation. 2014; 129: 51-56 Crossref PubMed Scopus (98) Google Scholar ]. However, it was not until 2004 [ [5] Kyrle P.A. et al. The risk of recurrent venous thromboembolism in men and women. N. Engl. J. Med. 2004; 350: 2558-2563 Crossref PubMed Scopus (397) Google Scholar ] when it was first shown and later confirmed [ 6 Douketis J. et al. Risk of recurrence after venous thromboembolism in men and women: patient level meta-analysis. BMJ. 2011; 342: d813 Crossref PubMed Scopus (214) Google Scholar , 7 McRae S. et al. Effect of patient's sex on risk of recurrent venous thromboembolism: a meta-analysis. Lancet. 2006; 368: 371-378 Abstract Full Text Full Text PDF PubMed Scopus (256) Google Scholar , 8 Baglin T. et al. High risk of recurrent venous thromboembolism in men. J. Thromb. Haemost. 2004; 2: 2152-2155 Crossref PubMed Scopus (110) Google Scholar ] that men had an unexplained 3.6-fold higher risk of recurrence of VTE than women that investigation into the effects of sex on VTE occurrence intensified. This line of research has had an impact on patient management. It is now recommended that patient sex among other factors be considered when determining duration of anticoagulation for unprovoked venous thrombosis [ [9] Kearon C. et al. Antithrombotic therapy for VTE disease: CHEST guideline and expert panel report. Chest. 2016; 149: 315-352 Abstract Full Text Full Text PDF PubMed Scopus (3362) Google Scholar , [10] Khan F. Le Gal G. Rodger M.A. Stopping anticoagulation in a woman with unprovoked venous thromboembolism. CMAJ. 2017; 189: E1112-E1114 Google Scholar ].