From the Journals

Focus of new ASH VTE guidelines: Thrombophilia testing



Thrombophilia testing should be limited to specific circumstances, including when venous thromboembolism (VTE) is provoked by nonsurgical risk factors such as pregnancy or oral contraception use, according to new clinical practice guidelines released by the American Society of Hematology. Individuals with a family history of VTE and high-risk thrombophilia, and those with VTE at unusual body sites should also be tested, the guidelines panel agreed.

“These guidelines will potentially change practice – we know that providers and patients will make a shared treatment decision and we wanted to outline specific scenarios to guide that decision,” panel cochair and first author Saskia Middeldorp, MD, PhD, explained in a press release announcing the publication of the guidelines in Blood Advances.

Dr. Middeldorp is a professor of medicine and head of the department of internal medicine at Radboud University Medical Center, Nijmegen, the Netherlands.

The guidelines are the latest in an ASH series of VTE-related guidelines. ASH convened a multidisciplinary panel with clinical and methodological expertise to develop the guidelines, which were subject to public comment, and they “provide recommendations informed by case-based approaches and modeling to ensure the medical community can better diagnose and treat thrombophilia and people with the condition can make the best decisions for their care,” the press release explains.

Thrombophilia affects an estimated 10% of the population. Testing for the clotting disorder can be costly, and the use of testing to help guide treatment decisions is controversial.

“For decades there has been dispute about thrombophilia testing,” Dr. Middeldorp said. “We created a model about whether and when it would be useful to test for thrombophilia, and based on the model, we suggest it can be appropriate in [the specified] situations.

The panel agreed on 23 recommendations regarding thrombophilia testing and management. Most are based on “very low certainty” in the evidence because of modeling assumptions.

However, the panel agreed on a strong recommendation against testing the general population before starting combined oral contraceptives (COC), and a conditional recommendation for thrombophilia testing in:

  • Patients with VTE associated with nonsurgical major transient or hormonal risk factors
  • Patients with cerebral or splanchnic venous thrombosis in settings where anticoagulation would otherwise be discontinued
  • Individuals with a family history of antithrombin, protein C, or protein S deficiency when considering thromboprophylaxis for minor provoking risk factors and for guidance related to the use of COC or hormone therapy
  • Pregnant women with a family history of high-risk thrombophilia types
  • Patients with cancer at low or intermediate risk of thrombosis and with a family history of VTE

“In all other instances, we suggest not testing for thrombophilia,” said Dr. Middeldorp.

The ASH guidelines largely mirror those of existing guidelines from a number of other organizations, but the recommendation in favor of testing for thrombophilia in patients with VTE provoked by a nonsurgical major transient risk factor or associated with COCs, hormone therapy, pregnancy or postpartum is new and “may cause considerable discussion, as many currently view these VTE episodes as provoked and are generally inclined to use short-term anticoagulation for such patients,” the guideline authors wrote.

“It is important to note, however, that most guidelines or guidance statements on thrombophilia testing did not distinguish between major and minor provoking risk factors, which current science suggests is appropriate,” they added.

Another novel recommendation is the suggestion to test for hereditary thrombophilia to guide the use of thromboprophylaxis during systemic treatment in ambulatory patients with cancer who are at low or intermediate risk for VTE and who have a family history of VTE.

“This new recommendation should be seen as a new application of an established risk stratification approach,” they said.

Additional research is urgently needed, particularly “large implementation studies comparing the impact, in terms of outcomes rates, among management strategies involving or not involving thrombophilia testing,” they noted.

The guideline was wholly funded by ASH. Dr. Middeldorp reported having no conflicts of interest.

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