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Do you think that the medical community has been too enthusiastic about testing for certain thrombophilic disorders?
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No consensus exists.
No general consensus exists as to which patients and family members should be tested for thrombophilias. At least five guidelines or consensus statements exist, varying markedly in recommendations as to who should be tested and who not, suggesting very limited testing, very liberal testing, or some intermediate level of testing.
The main reason I test patients is to detect a “strong” thrombophilia — antiphospholipid antibody syndrome, antithrombin deficiency, homozygous Factor V Leiden, double heterozygous Factor V Leiden plus prothrombin 20210 mutation, protein C deficiency, and protein S deficiency.
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Finding of a strong thrombophilia has a number of consequences in my practice. First, it decreases my threshold to recommend long-term anticoagulation in a patient who has had an episode of spontaneous venous thromboembolism. Second, in a patient with an unexplained arterial, non-arteriosclerotic thromboembolic event, it leads to a discussion about whether anticoagulant or antiplatelet therapy might be the preferred treatment for secondary prevention.
Finally, finding a strong thrombophilia prompts recommendation for testing of the identified inherited thrombophilia(s) in asymptomatic female family members. Advice is given against the use of estrogen birth control methods and for anticoagulation prophylaxis during the postpartum, and possibly the antepartum period.
Stephan Moll, MD, is an Associate Professor in the Department of Medicine, Division of Hematology-Oncology at the University of North Carolina School of Medicine, Chapel Hill.
Thrombophilia testing has been overused.
Thrombophilia testing has been overly abused by a number of clinicians.
We cannot make clinical decisions based on the results of thrombophilia tests, and the reality is that in most of the patients with thrombophilia, testing will not have a major impact, clinically speaking.
For some indications, thrombophilia is well established as a risk factor. However, it has been used in stroke, it has been used in ischemic heart disease, and I have even had requests to have patients tested for thrombophilia because they are going to have plastic surgery. Clinicians are using these tests with basically no existing evidence of their utility. I do not think that is justified.
For instance, the most common thrombophilia in Western countries is Factor V Leiden, which you will find frequently in patients with venous thrombotic disease. Factor V Leiden is a risk factor for a first thrombotic event but not for a second — thus, having a heterozygous Factor V Leiden does not really mean anything from a clinical standpoint, you would still manage the patient in the same way as if the patient had no thrombophilia and the risk for recurrence would be related to the thrombosis itself.
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A number of studies have looked at multiple defects, like patients who are homozygous or compound heterozygotes for some defects, and those studies have had somewhat contradictory results. Even still, the proportion of patients with these homozygous defects is, in reality, very small. Perhaps the one test that should be done more liberally is lupus anticoagulant or antiphospholipid antibodies because it does have clinical consequences should they be positive.
In the general community practice, it is probably not advisable to do thrombophilia testing because testing is often done and then it is unclear what to do with the results. Thrombophilia testing should be reserved for larger centers, for specialized practices, or for studies where you want to control for thrombophilia, for example, looking at the new anticoagulants for the treatment of venous thrombosis of any kind.
Alejandro Lazo-Langner, MD, MSc, is an Assistant Professor in the Hematology Division of the Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada.