Administrative Claims Analysis of the Relationship Between Warfarin Use and Risk of Hemorrhage Including Drug-Drug and Drug-Disease Interactions

Abstract

Only 2 of 5 combinations of warfarin with drugs in this study were found to be associated with a higher prevalence of hemorrhage compared with warfarin use alone. The absolute prevalence of hemorrhage in users of warfarin and metronidazole was 22.7% and 17.2% for warfarin and cephalosporins, respectively, versus 14.2% in users of warfarin alone. The prevalence of hemorrhage for concomitant use of warfarin and NSAIDs/COX-2 inhibitors, amiodarone, or fibric acid derivatives such as fenofibrate was not greater than for warfarin alone. Liver disease or HF in warfarin users was associated with a significant increase in the likelihood of hemorrhage.