In this study, Joseph Delaney MSc, Dr. James Brophy and colleagues looked for drug–drug interactions in 4,028 cases with a diagnosis of gastrointestinal bleeding and 40,171 matched controls in the United Kingdom. They documented a 4–6-fold increase in the rate of gastrointestinal bleeding associated with the combined use of the anticoagulant warfarin and antiplatelet agents. This real-world study of prescription data from general practices observed much higher rates of bleeding than those derived from a meta-analysis of randomized clinical trials. The authors write that physicians should be aware of these risks to better assess their patients’ therapeutic risk–benefit profiles.

In a related commentary, David Juurlink PhD explains the main drug interactions with the anticoagulant warfarin.-Canadian Medical Association Journal