Extended Follow-up of the Multi-Center Multi-National Prospective Cohort Study That Derived the “Men Continue and HERDOO2” Clinical Decision Rule Which Identifies Low Risk Patients Who May Be Able to Discontinue Oral Anticoagulants (Oac) 5-7 Months After Treatment for Unprovoked Venous Thromboembolism (VTE).

To continue or discontinue OAC after 6 months of therapy for VTE is one of the most important unanswered questions in VTE management. In 2007, we developed a clinical decision rule to identify low risk patients with unprovoked VTE who could safely discontinue OAC after 5-7 months of therapy. This clinical decision rule was developed from a large prospective cohort study of patients with unprovoked VTE who discontinued anticoagulants after 5-7 months of OAC and were subsequently followed for a mean of 18 months for recurrent VTE. The “MEN continue and HERDOO2” rule states that men and high risk women should continue anticoagulants indefinitely after unprovoked VTE. High risk women are women with ≥2 of the following 1)Hyperpigmentation, Edema or Redness (HER) on exam in either leg, 2)Vidas D-Dimer >250, 3)Obesity- BMI >30 or 4)Older age over 65. Given that the OAC treatment decision is a long-term treatment decision that needs to be counter-balanced with long-term bleeding risk from OAC (1-3% annual risk of major hemorrhage) it is important to determine long-term risks of recurrent VTE in unprovoked VTE patients, high risk patients and low risk patients.

We sought to confirm that the risk of recurrent VTE in high risk patients remains elevated and conversely that the risk remains low in low risk women over longer term follow-up.

Multi-centre prospective cohort study of first unprovoked VTE patients who had potential predictors collected while on OAC (including D-Dimer) enrolled from 2001 to March 2006. Patients were excluded if they had: 1) recurrent unprovoked VTE, 2) known high risk thrombophilia or 3) no consent. Symptomatic suspected VTE during subsequent follow-up (up to july 2009) off of OAC was investigated with reference to baseline imaging and then independently adjudicated.

646 participants were enrolled in 11 centers. At enrolment, mean age of 53 (range 17-95) and 49% were female. During a mean 3.1 years (range 0.01-6.5) of follow-up, 131/512 suspected VTE were adjudicated as recurrent VTE resulting in an annual risk of recurrent VTE of 6.7% (95% CI 5.5-7.6%) in patients with unprovoked VTE. Men had a 9.9% (95% CI 8.3-11.8%) annual risk of recurrent VTE. High risk women with 2 or more HERDOO points had an annual risk of recurrent VTE of 8.3% (95%CI 5.7-11.3%). Low risk women (1 or 0 HERDOO points) had 1.3% (95% CI 0.5-2.8%) annual risk of recurrent VTE compared to 9.5% (8.1-11.0%) annual risk of recurrent VTE in high risk patients (men and high risk women).

Men and high risk women with unprovoked VTE should be considered for long-term OAC therapy given a high risk of recurrent VTE over 3 year follow-up . Women with a low HER DOO 2 score may be able to safely discontinue anticoagulants.

Rodger:Bayer: Research Funding; Leo Pharma: Research Funding; Pfizer: Research Funding; Boehringer Ingelheim: Membership on an entity's Board of Directors or advisory committees; Biomerieux: Research Funding; GTC Therapeutics: Research Funding. Crowther:BI: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Bayer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria, Research Funding; Leo Pharma: Consultancy, Honoraria, Research Funding; Sanofi-Aventis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Artisan Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees.