Emergency department management of patients on warfarin therapy

Study objective: To characterize warfarin management in the emergency department (ED).

Methods: This was a retrospective, cross-sectional, observational study of patients who were receiving warfarin and were discharged from a tertiary care, academic urban ED between June and August 2007. We abstracted patient demographics, presenting complaint, international normalized ratio (INR) if tested, indication for warfarin if documented, new medications administered or prescribed in the ED, and discharge instructions. Presenting complaints were categorized according to whether they were warfarin-related and concerning for thrombosis or bleeding. The primary outcome measure was the prevalence of warfarin therapy. The secondary outcome measures were frequency with which ED providers obtained an INR result, response to nontherapeutic results, administration or prescription of interacting medications, and percentage of patients receiving recommendations for anticoagulation follow-up.

Results: Two percent (111/7,195) of all patients presenting to and discharged from the ED during the study period were found to be receiving warfarin. Seventy-one percent (79/111) had an INR checked. Nontherapeutic INRs were recorded for 49% (39/79) of patients; ED providers intervened to address these results in 21% (8/39) of cases. Seventy-one percent (5/7) of patients with a supratherapeutic INR received an intervention compared with 9% (3/32) of patients with a subtherapeutic INR. Seventeen percent (19/111) and 13% (14/111) of patients received or were prescribed potentially interacting medications, respectively. Recommendations for specific anticoagulation follow-up were documented for 19% (21/111) of all patients.

Conclusion: Patients receiving warfarin frequently present to the ED and often have nontherapeutic INRs. Potential areas for improvement in ED management include greater attention to subtherapeutic INRs, interacting medications, and discharge planning.