Use of specific indicators to detect warfarin-related adverse events

The use of specific indicators, or "triggers," to identify adverse drug events (ADEs) associated with warfarin therapy is described.

Automated triggers provided by laboratory and pharmacy data were used to identify potential ADEs associated with warfarin therapy among patients treated in the emergency room or admitted to six community hospitals between July 2002 and December 2003. The triggers consisted of an International Normalized Ratio (INR) of greater than 3.0 and pharmacy orders for vitamin K. Pharmacists reviewed the triggers monthly for clinical determination of ADEs during preintervention and postintervention periods. Interventions consisted of staff education and real-time adjustments in therapy. A 39% overall reduction in ADEs occurred between the preintervention and postintervention periods. Harmful ADEs declined by 70%.

INRs of greater than 3.0 and vitamin K administration appeared to be reliable indicators of warfarin-associated ADEs, and detection with these indicators appeared to reduce ADEs when combined with appropriate interventions.