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Reserve thrombophilia testing for select subgroups

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Knowledge is power

Clinical utility of thrombophilia testing is determined by the cost-benefit ratio to each patient. The extent of testing can be quite variable with the cost varying widely. Testing can range from factor V Leiden and homocystine levels to lupus anticoagulant and an isolated factor, or it can include panels of both fibrinolytic and thrombotic pathways as well as genetic testing. Duration of therapy and risk of recurrence can be influenced by the results. The real cost of underestimating the risk of recurrence is the sequela of recurrent thrombosis, such as the increased risk of valvular damage or obstruction, pulmonary embolism, and the development of the postthrombotic syndrome.

Even patients who have a provoked thrombus have been shown to have an increased incidence of thrombophilia. A positive test result can impact the patient’s treatment or potentially prevent events in families who have an unrecognized thrombophilic issue. Those outcomes matter to the patient and the family. In the past we ligated the saphenofemoral junction for patients with an isolated superficial vein thrombosis encroaching on the junction only to find out that many of these patients have an underlying undiagnosed thrombophilia, which had progressed to deep vein thrombosis.

Knowledge helps select appropriate therapies and potentially prevents life-threatening complications to the patient and their family members. Many people who have an underlying thrombophilia have a minor change in their baseline that then starts a cascade to promote a thrombotic event. Knowledge is power and testing to help identify risk is clinically warranted.

Treatments are based on risk factor assessment, which includes laboratory analysis, residual thrombus, and clinical risk. Understanding the fibrinolytic balance may further explain why some patients recanalize completely while other patients never recanalize and have a significant amount of residual thrombus.

Once a thrombophilia has been identified, family members can be tested for a specific defect, potentially avoiding any thrombotic events and preventing miscarriages in those of reproductive years. Further testing and identification of subgroups is needed to clearly define those who would benefit most. This will only be accomplished with further testing. Research can identify additional defects that will help treating physicians to further understand the thrombotic and fibrinolytic pathways. Management decisions need to be based on evidence. Some of these factors were unknown 20 years ago.

Dr. Joann Lohr is an associate program director at the Good Samaritan Hospital vascular surgery residency program and director of the John J. Cranley Vascular Laboratory at Good Samaritan Hospital, both in Cincinnati. She had no relevant financial disclosures.


 

FROM THE JOURNAL OF VASCULAR SURGERY: VENOUS AND LYMPHATIC DISORDERS

References

Clinicians should avoid routinely screening venous thromboembolism patients for thrombophilias, and should instead weigh the risks of recurrent thrombosis against the chances of bleeding with prolonged anticoagulation, according to a review article published in the April issue of the Journal of Vascular Surgery: Venous and Lymphatic Disorders.

“These laboratory tests are costly, and surprisingly, there is little evidence showing that testing leads to improved clinical outcomes,” said Dr. Elna Masuda at Straub Clinic and Hospital, Honolulu, and her associates. “Until data from well-designed, controlled trials are available comparing different durations of anticoagulation with specific thrombophilic states, treatment should be based on clinical risk factors and less on laboratory abnormalities.”

More than half of patients with an initial venous thromboembolism (VTE) episode had a positive thrombophilia screen in one study (Ann. Intern. Med. 2001;135:367-73), the reviewers noted. Testing, however, usually does not affect clinical management or prevent VTE recurrence, and it can cost more than $3,000 per patient, they said.

For these reasons, the American Society of Hematology, the National Institute for Health Care and Excellence, and the Society for Vascular Medicine discourage screening after an initial VTE episode if patients have a known cause or transient risk factor for thrombosis.

Testing also is unlikely to benefit patients with first-time unprovoked (or idiopathic) VTE, patients with a permanent risk factor for thrombosis such as cancer, or patients with arterial thrombosis or thrombosis of the retina or upper arm veins, Dr. Masuda and her associates said. And because recurrent VTE generally merits long-term anticoagulation, affected patients only should be screened if they are considering stopping treatment and test results could inform that decision, they added (J. Vasc. Surg. Venous Lymphat. Disord. 2015;3:228-35).

Some subgroups of patients, however, could benefit from targeted thrombophilia testing. The reviewers recommended antiphospholipid antibody testing if patients have a history of several unexplained pregnancy losses or another reason to suspect antiphospholipid syndrome. Patients with heparin resistance should be tested for antithrombin deficiency, and patients with warfarin necrosis or neonatal purpura fulminans should be tested for protein C and S deficiencies, they added.

Clinicians also should consider screening women with a personal or family history of VTE if they are pregnant and are considering anticoagulation or are considering oral contraceptives or hormone replacement therapy, Dr. Masuda and her associates said.

Screening such patients remains controversial, but it could help guide anticoagulation therapy before and after delivery or might help patients decide whether or not to take exogenous hormones. “In the subgroup of those pregnant or planning pregnancy, history of prior VTE and strong family history of thrombosis are two factors that appear to play a clinically important role in identifying those who may benefit from screening,” they concluded.

Patients who want to pursue testing need to understand that management is mainly based on clinical risk and that test results usually will not change treatment recommendations, the reviewers also emphasized. “If testing will change management, it may be appropriate to proceed,” they added. “If long-term anticoagulation is preferred on the basis of positive test results, the risk of bleeding should be considered.”

The researchers reported no funding sources. Dr. Masuda reported having served on the speakers bureau for Janssen Pharmaceuticals.

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