In a subsequent study to validate the HERDOO2, researchers found that the risk of recurrent major VTE was 3.0% in low-risk women who discontinued oral anticoagulants (OACs), 8.1% in high-risk women and men who discontinued OACs, 1.6% in high-risk women and men who continued OACs, and 7.4% in high-risk women who discontinued OACs (BMJ 2017;356:j1065).
“I think the HERDOO2 rule is working pretty well to determine a low-risk group of women, and it’s not an unreasonable tool to be using,” Dr. Wells said.
Other variables that might help clinicians predict a patient’s VTE recurrence include the presence of recurrent venous obstruction (adjusted HR 1.32), and older age (HR 1.01 for every 1 year increase).
D-dimer levels can also be helpful. “If the serial D-dimers are positive, stay on anticoagulants,” Dr. Wells advised. “If they’re negative, discontinue anticoagulants and have the D-dimer levels repeated monthly for 3 months. If positive or positive conversions, return to OAC therapy.”
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Dr. Philip S. Wells
In one study, the annual risk of a VTE was 3% in the negative D-dimer patients, compared with 6.1% in those who had a history of an unprovoked VTE (Blood 2014;124:196-203).