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.