Understanding Risk Factors Involved in Developing a Second Blood Clot.

Deep Vein Thrombosis

Recurrent, Idiopathic, Deep Vein Thrombosis, Pulmonary Embolism, Clinical Prediction Rule, Venous Thromboembolism, Risk Factors

The purpose of this study is to develop a way to predict which patients diagnosed with idiopathic blood clots can safely stop warfarin therapy after six months. We will use patient characteristics, blood test results and imaging test results to identify those patients who have the lowest risk of developing a new blood clot after warfarin is stopped.

The risk of recurrent VTE in patients with idiopathic VTE subsequent to three to six months of oral anticoagulant therapy remains high (5-27% per year). The risk of recurrent VTE, however, is not likely high enough to justify indefinite anticoagulation in all patients with a first idiopathic VTE due to the rate of major bleeding with oral anticoagulants (2-6% per year), the inconvenience and cost of oral anticoagulant therapy, monitoring of oral anticoagulant therapy (e.g. prescription costs, time off work to go for lab tests, parking etc) and the lifestyle limitations of oral anticoagulant therapy (avoidance of certain physical activities, dietary restrictions, avoidance of pregnancy). Further, as some have argued, perhaps all that anticoagulant therapy achieves is to delay recurrent VTE and, as a recent editorial suggested, a tailored approached is required to determine sub-groups who require lifelong anticoagulation. A means to stratify patients with idiopathic VTE to identify a group at low risk of recurrent VTE who could safely discontinue oral anticoagulants subsequent to six months of therapy would be a significant advance in the care of these patients.

None listed

Canada, France