Risk of Recurrent Venous Thromboembolism in Patients With Provoked Deep Vein Thrombosis of the Leg and/or Pulmonary Embolism: a Prospective Cohort Study

Venous thromboembolism (VTE) is a common disease with an incidence of 1-2/1000 persons per year. VTE is a chronic disease with a considerable risk of recurrence. Patients with unprovoked VTE, i.e. VTE in the absence of a temporary risk factor including surgery, cancer or immobilisation, have a high recurrence risk and indefinite anticoagulation is generally recommended. The recurrence risk of patients with VTE provoked by a transient risk factor is regarded as low. Discontinuation of anticoagulation after three months is recommended because the benefit of reducing the recurrence risk further by prolonged anticoagulation is outweighed by the bleeding risk. However, the newer direct oral anticoagulants are potentially associated with a lower bleeding risk than vitamin K antagonists. Because they are also meanwhile widely available and are convenient there is a trend towards prolonging anticoagulation also in patients with a VTE after a transient provoking factor. However, the definition of transient provoking factors is imprecise and a distinct categorization according to the risk of recurrence is lacking. Preliminary evidence suggests that the recurrence risk varies considerably between the different transient provoking factors. In a prospective cohort study, the investigators will include patients with a deep vein thrombosis or pulmonary embolism provoked by a transient risk factor defined according to Guidance of the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis (Kearon et al., J Thromb Haemost 2016; 14: 1480-3) after discontinuation of anticoagulation. The study endpoint is recurrent symptomatic VTE.