White blood cells contribute to patient-specific warfarin dose for Han Chinese.

Background Warfarin is the most commonly prescribed anticoagulant worldwide. Factors which influence warfarin's inter-individual requirements including age, weight, and genetic factors explained about 50% of dose variance, and unidentified factors still remain. The aim of this study was to explore whether white blood cell count affects warfarin dose requirements. Methods Three hundred and twenty-two patients suffering from venous thromboembolism (VTE) and taking warfarin were recruited in this study. Genotyping of selected genes was conducted and other information was collected using the Epidata software. Dosing algorithms were constructed by multivariate linear regression analyses. Results In addition to well-known factors such as age, body weight, CYP2C9*3, and VKORC1 c.1173C>T, white blood cell counts negatively related to warfarin dose requirements and contributed to warfarin variability in Han Chinese by about 0.6%. Conclusion White blood cell count has a small but significant contribution to warfarin dose requirements in Han Chinese. Chin Med J 2012;125(11):1960-1963