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Characteristics of ambulatory anticoagulant adverse drug events: a descriptive study
Andrea L Long1, Lisa Bendz, Monica M Horvath
1Duke University Health System, Duke Health Technology Solutions, 2424 Erwin Road, Durham, NC, USA. andrea.long@duke.edu.
Insights
Outpatient warfarin adverse drug events (ADEs) frequently cause bleeding and hospital admissions. Improving anticoagulation management through technology and patient engagement is crucial for patient safety.
Area of Science:
- Pharmacovigilance
- Clinical Pharmacy
- Patient Safety
Background:
- Adverse drug events (ADEs) in outpatient settings are common but poorly understood.
- Anticoagulant medications pose significant safety risks and are frequent causes of outpatient ADEs.
- This study evaluated ambulatory anticoagulation ADEs and associated patient factors at Duke University Health System.
Purpose of the Study:
- To assess the characteristics of ambulatory anticoagulation adverse drug events.
- To identify patient populations experiencing these events.
- To describe quality improvement strategies for anticoagulation management.
Main Methods:
- Retrospective chart review of ambulatory warfarin-related ADEs.
- Utilized an automated trigger surveillance system for patient identification (INR >3 and vitamin K administration).
- Evaluated event and patient characteristics, and described improvement strategies.
Main Results:
- 169 events in 167 patients identified (Dec 2006-Jun 2008).
- Median supratherapeutic INR was 6.1; 52.1% of events involved bleeding, with 64.8% classified as major.
- 59.2% of events contributed to hospital admission; 24.9% of patients initiated therapy within 3 months prior.
Conclusions:
- Ambulatory warfarin ADEs lead to significant bleeding and hospitalizations.
- Improvements needed in anticoagulation management, including IT support for monitoring and documentation.
- Recommendations include avoiding drug interactions and enhancing patient engagement in care.
Background:
Despite the high frequency with which adverse drug events (ADEs) occur in outpatient settings, detailed information regarding these events remains limited. Anticoagulant drugs are associated with increased safety concerns and are commonly involved in outpatient ADEs. We therefore sought to evaluate ambulatory anticoagulation ADEs and the patient population in which they occurred within the Duke University Health System (Durham, NC, USA).
Methods:
A retrospective chart review of ambulatory warfarin-related ADEs was conducted. An automated trigger surveillance system identified eligible events in ambulatory patients admitted with an International Normalized Ratio (INR) >3 and administration of vitamin K. Event and patient characteristics were evaluated, and quality/process improvement strategies for ambulatory anticoagulation management are described.
Results:
A total of 169 events in 167 patients were identified from December 1, 2006-June 30, 2008 and included in the study. A median supratherapeutic INR of 6.1 was noted, and roughly half of all events (52.1%) were associated with a bleed. Nearly 74% of events resulted in a need for fresh frozen plasma; 64.8% of bleeds were classified as major. A total of 59.2% of events were at least partially responsible for hospital admission. Median patient age was 68 y (range 36-95 y) with 24.9% initiating therapy within 3 months prior to the event. Of events with a prior documented patient visit (n = 157), 73.2% were seen at a Duke clinic or hospital within the previous month. Almost 80% of these patients had anticoagulation therapy addressed, but only 60.0% had a follow-up plan documented in the electronic note.
Conclusions:
Ambulatory warfarin-related ADEs have significant patient and healthcare utilization consequences in the form of bleeding events and associated hospital admissions. Recommendations for improvement in anticoagulation management include use of information technology to assist monitoring and follow-up documentation, avoid drug interactions, and engage patients in their care.
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