The development and validation of a novel genetic-based warfarin dosing nomogram

Warfarin has been used as an anticoagulant for various thromboembolic disorders for over 60 years with an estimated two million new prescriptions per year. However, due to a very narrow therapeutic index and a large inter-patient variability in dose requirements, its use results in more serious adverse events annually than any other medication. Recent advances in the field of pharmacogenomics have resulted in a focus on the development of warfarin dosing algorithms that include genetic and non-genetic information. Several of these algorithms have proved very promising in research settings, but their application in clinical practice has not been fully validated. One of difficulties with the current genetic-based algorithms is that they are multi-factor equations derived from regression analysis. The goal of this research is to develop and evaluate a simple genetic-based warfarin dosing algorithm that would be practical to use in a typical clinical practice setting. The result of this research is a validated, tabular nomogram that does not require any calculations to predict a practical warfarin dosage regimen.