Geoffrey Barnes, MD, MScAssistant ProfessorVascular and Cardiovascular MedicineUniversity of Michigan

Many Patients Taking Warfarin Plus Aspirin Without Clear Indication Interview with:

Geoffrey Barnes, MD, MScAssistant ProfessorVascular and Cardiovascular MedicineUniversity of Michigan

Dr. Barnes

Geoffrey Barnes, MD, MSc
Assistant Professor
Vascular and Cardiovascular Medicine
University of Michigan What is the background for this study? What are the main findings?

Response: Both aspirin and warfarin are commonly used medications meant to prevent thrombotic complications, but might increase rates of bleeding complications.

We used a multi-center anticoagulation collaborative to explore how often patients being treated with warfarin were also taking aspirin but without a clear indication. We found that more than one-third (37.5%) of warfarin-treated patients without a clear reason for aspirin therapy were receiving aspirin. And these patients on both warfarin and aspirin experienced higher rates of bleeding and emergency department visits for bleeding than the patients taking warfarin alone. There were no differences in the rate of thrombotic events between the patients taking warfarin alone or those taking warfarin plus aspirin. What should readers take away from your report?

Response: It is important to review medication lists with patients. Many patients who take oral anticoagulants (such as warfarin) may also be taking aspirin without any clear indication. What recommendations do you have for future research as a result of this work?

Response: While we know that combination warfarin + aspirin therapy increases the risk of bleeding complications, we need to study the impact of stopping aspirin therapy when there is no clear indication. Will this decrease the risk of bleeding complications? Will the thrombotic complication rates remain low? These are important next research questions to explore. 

Any disclosures? I receive grant funding from Bristol-Myers Squibb, Pfizer, NHLBI, and Blue Cross Blue Shield of Michigan. I have consulted for Bristol-Myers Squibb, Pfizer, Janssen, and Portola.


Schaefer JK, Li Y, Gu X, et al. Association of Adding Aspirin to Warfarin Therapy Without an Apparent Indication With Bleeding and Other Adverse Events. JAMA Intern Med. Published online March 04, 2019. doi:10.1001/jamainternmed.2018.7816

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Last Updated on March 5, 2019 by Marie Benz MD FAAD