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

ABSTRACT 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.