Concomitant coumarin-NSAID therapy and risk for bleeding.

Abstract

To investigate the risk of bleeding complications during the combined use of coumarin derivatives and nonsteroidal antiinflammatory drugs (NSAIDs) compared with the use of coumarin derivatives alone. In this 1-year observational study, the local outpatient anticoagulation office detected all coumarin users with bleeding complications. These patients were sent questionnaires regarding the type and consequences of the bleeding as well as previous NSAID use. The local pharmacists detected patients with concomitant coumarin and NSAID prescriptions (but no bleeding). The relative risk for bleeding due to concomitant coumarin and NSAID use was estimated. During 1 year, 738 hemorrhages were identified in 681 coumarin users. In 12.2% of these cases, an NSAID was involved. In contrast, in the whole population of coumarin users, 2.5% were prescribed an NSAID. Therefore, the relative risk of NSAID use with regard to bleeding complications was 5.8 (95% CI 2.3 to 13.6). NSAID use during coumarin therapy considerably increases the bleeding risk compared with coumarin therapy alone. Although in daily practice these medications are frequently prescribed concomitantly, our results underscore the contraindication of concomitant use of NSAIDs and coumarin derivatives.