Troublesome Thrombophilia Testing
A ClinLabNavigator blog posted on July 23 reviewed the four P’s of thrombophilia testing. Testing for inherited thrombophilia is controversial. Two recent articles in the Journal of American Medical Association and the New England Journal of Medicine provide more guidance on laboratory testing for venous thromboembolism.
The JAMA article was entitled, “Thrombophilia testing in provoked venous thromboembolism: A teachable moment. The authors presented a case of a 52 year old woman who developed a venous thromboembolism (VTE) in her calf 4 days after total hip arthroplasty for a femoral neck fracture. Large panels of laboratory tests for thrombophilia were ordered in the next 48 hours. Protein C, Protein S and Antithrombin activity were all decreased. She was started on warfarin therapy and discharged from the hospital, with instructions to return to the hematology clinic two weeks later. The patient was worried that she had 3 rare disorders that might affect her children. During that appointment, the hematologist explained that these tests were spuriously decreased because they were performed during an acute event. Three months of anticoagulation therapy were recommended.
Medicare data indicates that up to 55% of patients with provoked VTE undergo thrombophilia testing. Medicare claims for 280,000 tests for inherited thrombophilia in 2014 cost an estimated $300 to $670 million.
The authors concluded their teaching moment by reviewing the recommendation from the Choosing Wisely campaign that thrombophilia testing should not be performed in adult patients with a transient risk factor who develop a VTE. Results of inherited thrombophilia testing are unlikely to change management, increase financial burden and increase the risk of harm due to inappropriate anticoagulation.
The NEJM article explained that available data does not show any differences in rates of recurrent VTE in patients who undergo testing for inherited VTE and those who do not. The significance of either positive or negative results in often misinterpreted by clinicians. Patients with positive results are often overtreated and kept on anticoagulant therapy indefinitely. Providers may falsely assume that patients with negative results, and their family members, are at low risk of future VTE.
This article further stated that no validated testing guidelines have been published. The American College of Chest Physicians does not give guidance on thrombophilia testing in its ninth edition of clinical practice guidelines for antithrombotic therapy or its 2016 VTE update. The American Society of Hematology’s 2013 Choosing Wisely campaign recommends not testing for thrombophilia in adults with VTE who have major transient risk factors.
Both articles are welcome reminders that thrombophilia testing should not be ordered at the time of presentation. I recommend reading both of these articles in their entirety.
Gupta A, Sarode R and Nagalla S. Thrombophilia testing in provoked venous thromboembolism: A teachable moment. JAMA Internal Medicine, published online June 5, 2017.
Connors JM. Thrombophilia testing and venous thrombosis. New England J Medicine, 2017; 377:1177-87.
