What genetic tests are recommended for a patient on Eliquis (apixaban)?

Genetic Testing Recommendations for Patients on Apixaban

For patients on apixaban (Eliquis), genetic testing for thrombophilia is generally not recommended unless specific clinical criteria are met, as testing rarely alters management of patients already on anticoagulation. 1

Appropriate Indications for Thrombophilia Testing

Genetic testing should be considered in the following specific situations:

• Age under 50 years with venous thrombosis
• Venous thrombosis in unusual sites (hepatic, mesenteric, cerebral veins)
• Recurrent venous thrombosis
• Strong family history of thrombotic disease
• Venous thrombosis in pregnant women or women taking oral contraceptives
• Relatives of individuals with venous thrombosis under age 50
• Women with recurrent pregnancy loss, unexplained severe preeclampsia, placental abruption, intrauterine growth restriction, or stillbirth 2, 1

Recommended Genetic Tests When Indicated

If testing is clinically indicated based on the above criteria, the following tests should be ordered:

1. Factor V Leiden mutation (R506Q) - This is the most common hereditary thrombophilia 2, 1
2. Prothrombin G20210A variant - The second most common hereditary thrombophilia 2, 1
3. Functional assays for:
   • Protein C deficiency
   • Protein S deficiency
   • Antithrombin III deficiency 2, 1
4. Plasma homocysteine levels - Especially important in patients positive for Factor V Leiden 2, 1

When Testing Is Not Recommended

Genetic thrombophilia testing is not recommended in:

• Patients over 50 years with venous thrombosis and no other risk factors
• Patients with arterial thrombotic disorders (except young female smokers with MI)
• Random screening of the general population
• Routine screening of asymptomatic women using oral contraceptives 2, 1

Impact on Management for Patients Already on Apixaban

For patients already on apixaban for DVT/PE:

• Thrombophilia testing has limited clinical utility in most cases
• The decision to continue anticoagulation should be based primarily on:
  • Clinical risk factors for recurrence
  • Whether the thrombotic event was provoked or unprovoked
  • The patient's bleeding risk 1

Special Considerations

• If Factor V Leiden testing is positive, additional testing for other thrombophilias is recommended as the presence of multiple genetic risk factors significantly increases thrombosis risk 2
• Patients with antithrombin, protein C, or protein S deficiency have much higher annual incidences of venous thrombosis (1.52-1.90%) compared to those with Factor V Leiden or prothrombin mutations (0.34-0.49%) 3
• The cumulative recurrence rates in relatives with antithrombin, protein C, or protein S deficiency are 19% at 2 years, 40% at 5 years, and 55% at 10 years 3

Testing Methodology

When genetic testing is indicated:

• Direct DNA-based genotyping is recommended for Factor V Leiden and prothrombin G20210A
• Functional assays should be used for protein C, protein S, and antithrombin III deficiencies
• Patients who test positive by functional assays should have confirmatory DNA testing 2

Remember that while genetic testing can identify thrombophilia, for patients already on apixaban, the test results rarely change management decisions regarding anticoagulation duration or dosing.