Venous thrombosis: who should be screened for thrombophilia in 2014?
Venous thromboembolism (VTE) is a chronic disease. Recurrence can be prevented by anticoagulants, albeit at the cost of bleeding. Assessing the risk of recurrence is important to balance the risks and benefits of anticoagulation. Numerous laboratory risk factors of VTE have been identified, which has lead to a practice called laboratory thrombophilia screening--a procedure in which patients with a prior VTE are systematically offered laboratory testing with the purpose of identifying the risk factors. The knowledge of these factors should improve counseling patients regarding their duration of anticoagulation. However, this approach has failed. For some factors including coagulation inhibitors and phospholipid antibodies, the evidence that they increase the recurrence risk is weak. The extent to which other defects (factor V Leiden, prothrombin mutation) increase the recurrence risk is irrelevant. Patients can have multiple risk factors, and it is unknown to what extent their interactions increase the recurrence risk. Some assay systems have technical limitations, which restrict their general applicability. Meaningful studies comparing treatment strategies regarding the recurrence risk in VTE patients with a distinct laboratory abnormality are lacking. Routine testing for heritable defects can cause unnecessary concerns and uncertainty both in patients and relatives, and might also lead to overtreatment. The absence of a laboratory abnormality does not necessarily mean that the recurrence risk is low. A negative result could thus potentially result in a false sense of safety for patients and physicians, and consequently in undertreatment. In summary, routine laboratory thrombophilia screening is no longer warranted.