An expanded pharmacogenomics warfarin dosing table with utility in generalised dosing guidance

Area of Science:

• Pharmacogenomics
• Clinical Pharmacology
• Genetics

Background:

• Pharmacogenomics (PGx) guided warfarin dosing aims to optimize dosage and reduce adverse drug reactions.
• Current genotype-dosing tables, like the FDA's, offer a basic risk assessment for warfarin anticoagulation.
• There is a need for more precise tools to interpret genetic data for warfarin therapy.

Purpose of the Study:

• To develop and validate an expanded gene-based warfarin dosing table (CPMC-WD table).
• To compare the predictive accuracy of the CPMC-WD table against existing methods for warfarin dosing.

Main Methods:

• A publicly available warfarin dosing calculator was used to create the CPMC-WD table.
• The table incorporates nine genetic variants in CYP2C9, VKORC1, and CYP4F2.
• Validation was performed using two datasets: a European American cohort (EUA, n=73) and the Quebec Warfarin Cohort (QWC, n=769).

Main Results:

• The CPMC-WD table demonstrated significantly higher accuracy in predicting therapeutic warfarin dose compared to the FDA table in both EUA (51% vs 33%) and QWC (52% vs 37%) cohorts.
• The CPMC-WD table also outperformed standard 5 mg/day dosing and a clinical-only algorithm in predicting therapeutic doses.
• Statistical significance was observed in comparisons across both cohorts (p<0.05, with some p<1×10(-6)).

Conclusions:

• The CPMC-WD table provides a more accurate prediction of therapeutic warfarin dose than the current FDA table.
• This expanded gene-based dosing table represents a valuable update for pharmacogenomic dosing guidelines.
• The CPMC-WD table can serve as an improved clinical decision support tool for warfarin therapy.