A clinical decision rule (CDR) – called the HERDOO2 rule – that can be applied to women after a first, unprovoked venous thromboembolism (VTE) was able to identify those with a low-risk of recurrence who could safely discontinue anticoagulation therapy. These results from the REVERSE II Trial were presented Aug. 30 during ESC Congress 2016 in Rome.

The multi-national trial tested the HERDOO2 rule on a total of 2,779 patients (mean age 54.4 years) with a first, unprovoked VTE who had completed between five and 12 months of anticoagulation therapy. The HERDOO2 rule is named for four risk factors that must be considered in determining a patient’s risk of VTE recurrence: 1) hyperpigmentation, edema or redness in either leg; 2) D-dimer > 250 μg/ml on anticoagulants; 3) obesity with body mass index (BMI) > 30 kg/m2 ; and 4) older than 65 years. According to the rule, women (but not men) are considered low-risk if they have only one, or none of these risk factors.

After drop-outs and exclusions, 622 women were considered low-risk, based on HERDOO2 criteria, and the majority discontinued anticoagulation therapy. Most of the 591 women considered to be high-risk, as well as 1,534 men for whom the HERDOO2 rule is not applicable, continued anticoagulation therapy. At one year, low-risk women who had discontinued anticoagulants had a 3 percent rate of recurrent VTE per patient year (the primary outcome), compared to an 8.1 percent rate in high-risk patients who discontinued. The rate was 1.6 percent in high-risk patients who continued.

Researchers did note that a sub-group of post-menopausal women aged 50 and above had a higher than expected rate of recurrent VTE (5.7 percent) when anticoagulants were discontinued, even if they were considered low-risk per the HERDOO2 rule. Further validation of the rule on post-menopausal women is necessary, they said.

“This is an important finding as, using our rule, over half of women with unprovoked VTE, can safely discontinue anticoagulants and be spared the burdens, costs, and risks of lifelong anticoagulation,” said study investigator Marc Rodger, MD. “Since current consensus guidelines suggest anticoagulants should be continued indefinitely in all patients with unprovoked VTE and non-high bleeding risk, our results are potentially practice-changing.”

Keywords: ESC Congress, Anticoagulants, Male, Risk Factors, Venous Thromboembolism

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