Combination Therapy – Aspirin & Warfarin

Publication Date: 
Thu, 11/01/2012
By: Alere Staff

The American Heart Association’s Journal STROKE published an August 2004 a review on the risks of major bleeding with combining aspirin with warfarin.1 One’s immediate reaction suggests the two should not be used together and perhaps even cancelled the other; however, an interesting finding resulted.

Of the 10,093-warfarin patients, 19.4% or 1, 958 patients received warfarin and aspirin therapy. Aspirin therapy was more common in coronary disease as one would expect. Major bleeding rates were surprisingly low with rates ranging from 1.3%-1.9%. Patients that experienced the highest bleeding events were those patients with a previous history of bleeding events. Even those patients experienced a low rate of 2.4%.1

Theresa I. Shireman, PhD, RPh and her colleagues at the University of Kansas Pharmacy provided some reassurance that the benefit of the therapy might outweigh the risks of using aspirin combined with a vitamin K antagonist like warfarin. The authors concluded there was “modest” risk of using the two therapies in combination.1

While not present in the retrospective study analysis above, it has been suggested that patients at increased risk for bleeding check their INRs more frequently. Home INR monitoring will help improve your control of warfarin. Studies have shown that increasing testing frequency with weekly testing of INR improves patient safety and helps keep the drug in its therapeutic effective zone.2,3 Weekly testing was shown to be the most effective testing frequency.2 Medicare and many private/commercial insurance reimburse patients for weekly patient self-testing.4 Go to the Getting Started page or call Alere at 1.800.504.4032 for more information about testing your INR at home.

  1. Shireman, Theresa I., et al. Combined Anticoagulant – Antiplatelet Use and Major Bleeding Events in Elderly Atrial Fibrillation Patient. Stroke. 2004;35:2362-2367.
  2. Am J Manag Care. 2014;20(3):202-209.
  3. Heneghan C., et al. Self-monitoring of oral anticoagulation: a systematic review and meta-analysis. 2006. Lancet, 367, 404-11.
  4. Center for Medicare and Medicaid Services. Decision Memo for Prothrombin Time (INR) Monitor for Home Anticoagulation Management  (CAG-00087R) [Memorandum]. 2008. Baltimore, MD.