HERDOO2 Rule for Anticoagulation Discontinuation After Unprovoked Venous Thromboembolism

1. See Also
   1. Anticoagulation in Thromboembolism
   2. Venous Thromboembolism
   3. Thrombophilia
2. Indications
   1. Assess a woman's risk of recurrent Venous Thromboembolism (VTE) after stopping Anticoagulation
   2. Assumes first unprovoked VTE in a woman over age 18 years old
3. Contraindications
   1. Male gender
      1. HERDOO2 was only developed to assess risk in women
      2. Male gender alone is a risk for recurrent VTE (RR 1.8 in unprovoked VTE)
         1. Douketis (2011) BMJ 342: d813 [PubMed]
   2. Identified Thromboembolism risk
      1. Leg Fracture or lower extremity plaster cast
      2. Immobilization >3 days
      3. General Anesthesia within last 3 months
      4. Cancer diagnosis within the last 5 years
4. Criteria (Score 1 point for each positive)
   1. Positive D-Dimer
      1. D-Dimer >250 ng/ml D-Dimer Units (DDU) or
      2. D-Dimer >0.5 mcg/ml Fibrinogen Equivalent Units or (FEU)
   2. Body Mass Index (BMI) >=30 kg/m2
   3. Age >= 65 years old
   4. Post-Thrombotic Signs (e.g. edema, erythema, Hyperpigmentation)
5. Interpretation
   1. Score 0 to 1: Low Risk (3% recurrent major VTE Risk in 100 person years)
      1. May discontinue Anticoagulation after initial unprovoked VTE management
   2. Score 2 to 4: Higher Risk (7.4% recurrent major VTE Risk in 100 person years)
      1. Continue longterm Anticoagulation after initial unprovoked VTE management
6. Resources
   1. HERDOO2 Rule for Discontinuing Anticoagulation in Unprovoked VTE (MDCalc)
      1. https://www.mdcalc.com/herdoo2-rule-discontinuing-anticoagulation-unprovoked-vte
7. References
   1. Rodger (2017) BMJ 356 :j1065 +PMID:28314711 [PubMed]