Pharmacogenetic Warfarin Dosing Algorithms: Validity in Egyptian Patients.

BACKGROUND/AIMS: Data from previous reports, addressing the significance of genotype-guided dosing of warfarin in Egyptian patients, are infrequent and controversial. This study is aimed at demonstrating the validity of genetic dosing algorithms in Egyptian patients on warfarin therapy. METHODS: A total of 100 Egyptian patients on a stable maintenance daily dose of warfarin were enrolled. The predicted warfarin dose for each patient was calculated using the warfarin dosing table, the Gage and the International Warfarin Pharmacogenetics Consortium (IWPC) clinical algorithms and the Gage and the IWPC genetic algorithms and compared to the actual dose. The accuracy of warfarin dosing algorithms was assessed by using the linear regression analysis. RESULTS: The most accurate model in predicting the ideal dose was the Gage genetic algorithm by R2 of 50.4% and the IWPC genetic algorithm by R2 of 42.3%, followed by the warfarin dosing table by R2 of 19.1%, and the Gage clinical algorithm by R2 of 18.9% and the least accurate was the IWPC clinical algorithm by R2 of 9.4%. CONCLUSIONS: The Gage -genetic warfarin dosing algorithm is the best model that could be implemented in Egyptian patients starting warfarin therapy.