title: Influence of hereditary or acquired thrombophilias on the treatment of venous thromboembolism.
abstract: OBJECTIVE
  Deficiency of antithrombin, protein C, and protein S increases the risk of a first venous thromboembolism (VTE) by at least 10-fold and is rare (i.e., <0.5% of population), whereas factor V Leiden and the prothrombin G20210A gene increase this risk by 2-5-fold and are common (2-5% of whites). Antiphospholipid antibodies are considered acquired thrombophilic states. Testing for these abnormalities is widespread. This review will consider if the results of testing should influence how patients with VTE are treated.
  
  
  RESULTS
  There are no randomized trials that have compared testing for thrombophilia with no testing; consequently, current assessments of whether testing should influence treatment of VTE are based on indirect evidence. Observational studies indicate that anticoagulants are equally effective in patients with and without thrombophilia; therefore, the presence of thrombophilia should not influence the choice of anticoagulant or the intensity of therapy. A lupus anticoagulant, however, can complicate monitoring of vitamin K antagonist therapy. The risk of recurrent VTE after stopping anticoagulant therapy may be higher in patients with thrombophilia, but not enough to influence whether anticoagulants should be stopped at 3 months or continued indefinitely.
  
  
  CONCLUSIONS
  Thrombophilia should rarely influence the treatment of VTE. Therefore, routine thrombophilia testing of patients with VTE is not indicated as a way to guide treatment decisions.
authors: McMaster University, Hamilton, Ontario, Canada. kearonc@mcmaster.ca
authors: Clive
authors: C
authors: Kearon
mesh_terms: D000925:Anticoagulants / Q000627:therapeutic use*; D006801:Humans; D008403:Mass Screening; D018570:Risk Assessment; D019851:Thrombophilia / Q000150:complications / Q000175:diagnosis*; D054556:Venous Thromboembolism / Q000188:drug therapy*
chemical_list: D000925:Anticoagulants