Apixaban for extended treatment of venous thromboembolism. N Engl J Med. 2013;368(8): 699-708. 49. Castellucci LA, Cameron C, Le Gal G, et al. Ef cacy and safety outcomes of oral anticoagulants and antiplatelet drugs in the secondary prevention of venous thromboembolism: systematic review and network meta-analysis. BMJ. 2013;347:f5133. 50. Sobieraj DM, Coleman CI, Pasupuleti V, Deshpande A, Kaw R, Hernandez AV. Comparative ef cacy and safety of anticoagulants and aspirin for extended treatment of venous thromboembolism: a network meta-analysis. Thromb Res. 2015;135(5):888-896. 51. Iorio A, Kearon C, Filippucci E, et al. Risk of recurrence after a rst episode of symptomatic venous thromboembolism provoked by a transient risk factor: a systematic review. Arch Intern Med. 2010;170(19):1710-1716. 52. Boutitie F, Pinede L, Schulman S, et al. In uence of preceding length of anticoagulant treatment and initial presentation of venous thromboembolism on risk of recurrence after stopping treatment: analysis of individual participants data from seven trials. BMJ. 2011;342:d3036. 53. Prandoni P, Noventa F, Ghirarduzzi A, et al. The risk of recurrent venous thromboembolism after discontinuing anticoagulation in patients with acute proximal deep vein thrombosis or pulmonary embolism. A prospective cohort study in 1,626 patients. Haematologica. 2007;92(2):199-205. 54. Prandoni P, Lensing AWA, Cogo A, et al. The long-term clinical course of acute deep venous thrombosis. Ann Intern Med. 1996;125(1):1-7. 55. Palareti G, Legnani C, Lee A, et al. A comparison of the safety and ef cacy of oral anticoagulation for the treatment of venous thromboembolic disease in patients with or without malignancy. Thromb Haemost. 2000;84(5):805-810. 56. Baglin T, Douketis J, Tosetto A, et al. Does the clinical presentation and extent of venous thrombosis predict likelihood and type of recurrence? A patient level meta-analysis. J Thromb Haemost. 2010;8(11):2436-2442. 57. 