CADTH undertook a project on genetic testing for factor V Leiden and prothrombin gene mutations — both of which can lead to an increased risk of developing blood clots (thrombophilia). The project examines the use of these tests in patients who have experienced a first blood clot in the absence of other risk factors. When patients experience an unprovoked venous thromboembolic event (VTE) such as deep vein thrombosis (DVT) or pulmonary embolism (PE), testing may help to determine the risk for future recurrence and appropriate clinical management.
While the genetic tests to identify factor V Leiden or prothrombin thrombophilia are available and reimbursed in Canada, there is a lack of clarity regarding when the genetic tests should be ordered and how the tests might impact patient management or improve patient health outcomes.
The objective of this project was to determine, for patients with a first unprovoked VTE:
- How effective the tests are in identifying a patient's future risk of recurrent VTE
- The risks and benefits of testing
- The cost-effectiveness of the tests.
Based on these assessments and clinical expertise, CADTH’s Health Technology Expert Review Panel (HTERP) developed the following recommendation:
HTERP recommends that patients with a first unprovoked VTE should not routinely be tested for factor V Leiden and prothrombin mutations.
Our project on factor V Leiden and prothrombin mutation testing in patients with unprovoked thromboembolism resulted in the following reports: