Concomitant coumarin-NSAID therapy and risk for bleeding.
OBJECTIVE
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.


METHODS
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.


RESULTS
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).


CONCLUSIONS
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.
Knijff-Dutmer
Ellen A J
EA
Department of Rheumatology, Medisch Spectrum Twente, Enschede, The Netherlands. eajkniff@hotmail.com
Schut
Gelte A
GA
van de Laar
Martin A F J
MA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000009:adverse effects* / Q000627:therapeutic use; D000925:Anticoagulants / Q000009:adverse effects* / Q000627:therapeutic use; D015331:Cohort Studies; D003374:Coumarins / Q000009:adverse effects* / Q000627:therapeutic use; D004347:Drug Interactions; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced* / Q000453:epidemiology; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D012307:Risk Factors; D011795:Surveys and Questionnaires
D000894:Anti-Inflammatory Agents, Non-Steroidal; D000925:Anticoagulants; D003374:Coumarins; C030123:coumarin