Genotype-Guided vs Clinically-Guided Stable Warfarin Dose Prediction and Stable Dose Establishment In A Predominantly Non-European Ancestry Population

Background Warfarin dosing varies due to individual genetic and clinical factors. The utility of genotype-guided warfarin dosing to improve stable warfarin dose is not extensively studied in non-European populations. Research design and methods Retrospective cohort study of patients initiating warfarin receiving genotype (PGx)-guided or clinically guided dosing. Primary outcomes included dose discordance between estimated dose at discharge and eventual stable dose. Results No significant difference in warfarin dose discordance was observed (PGx: 9.1 +/- 8.8 mg/week difference vs. Clinical: 7.9 +/- 8.9 mg/week difference; P = 0.446). PGx-guided dosing did not reduce time to achieve stable dose (1.8 +/- 2.5 months vs. 2.1 +/- 2.6 months; P = 0.508). Vitamin K intake level did not alter prediction accuracy or time to stable dose (PGx-predicted: dose difference P = 0.493, time to stable dose P = 0.336; Clinically predicted: dose difference P = 0.145, time to dose INR P = 0.095). Conclusions PGx-guided warfarin dosing did not improve eventual stable dose discordance or reduce the time to achieve stable dose in this predominantly non-European cohort. Dietary vitamin K intake level did not impact warfarin dose discordance or time to achieve stable warfarin dose. Additional study is needed to identify populations that best benefit from PGx-guided warfarin dosing.