Update to Atrial Fibrillation – Anticoagulation: Warfarin initiation

27 Oct Update to Atrial Fibrillation – Anticoagulation: Warfarin initiation

All TreatGx users now have access to the updated treatment algorithm for Atrial Fibrillation – Anticoagulation: Warfarin.

Warfarin dosing update

The atrial fibrillation anticoagulation algorithm now provides updated dosing information for warfarin, including recommendations from the Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for Pharmacogenetics-Guided Warfarin Dosing: 2017 Update [1]. Notably, studies have found that conventional pharmacogenetic algorithms for warfarin dosing do not perform acceptably in African Americans when used without specific modifications for CYP2C9 star alleles frequently found in the African population [1]. CPIC guidelines include modifications for those with African ancestry and our update seeks to address those inequities in clinical guidance.

Highlights of the update include:

• Calculations done using the International Warfarin Pharmacogenetics Consortium (IWPC) pharmacogenetic algorithm [2], a validated algorithm recommended by CPIC.
• Inclusion of CPIC recommendations for those of African ancestry with tested CYP2C9 *5, *6, *8, and *11 star alleles.
• Inclusion of dosing adjustments for carriers of CYP4F2 rs2108622 T allele
• Inclusion of dosing adjustments for those with African ancestry who are carriers of rs12777823 A allele.
• Additional adjustment information for different INR targets and smokers, using recommendations from the Anderson warfarin dosing algorithm [3].

References

1. Johnson, J. et al. Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for Pharmacogenetics-Guided Warfarin Dosing: 2017 Update. Clinical Pharmacology & Therapeutics 102, 397-404 (2017).
2. Klein TE, Altman RB, Eriksson N, et al. Estimation of the warfarin dose with clinical and pharmacogenetic data. The New England journal of medicine. 2009;360(8):753-764.
3. Anderson JL, Horne BD, Stevens SM, et al. A randomized and clinical effectiveness trial comparing two pharmacogenetic algorithms and standard care for individualizing warfarin dosing (CoumaGen-II). Circulation. 2012;125(16):1997-2005.