Concurrent Use of Warfarin and Antibiotics and the Risk of Bleeding in Older Adults: Baillargeon J, Holmes HM, Lin Y, Raji MA, Sharma G, Kuo YF. Am J Med 2012;125:183–9.

Abstract

This was a case-control cohort study that investigated the risk of bleeding in older adults on chronic warfarin with concurrent use of any of six commonly prescribed antibiotic classes: azole antifungals, macrolides, quinolones, cotrimoxazole, penicillins, or cephalosporins. The study used data from the Medicare Part D prescription drug program to identify 38,762 adults aged > 65 years on chronic warfarin and followed them for a study period of 1 year (2008), and recorded cases of bleeding events requiring hospitalization and their association with antibiotic exposure, divided by recency of exposure as: 0–15 days, 16–60 days, or > 60 days.