Failure mode and effects analysis to reduce risk of anticoagulation levels above the target range during concurrent antimicrobial therapy

Abstract

Purpose: A failure mode and effects analysis (FMEA) was conducted to analyze the clinical and operational processes leading to above-target International Normalized Ratios (INRs) in warfarin-treated patients receiving concurrent antimicrobial therapy.

Methods: The INRs of patients on long-term warfarin therapy who received a course of trimethoprim-sulfamethoxazole, metronidazole, fluconazole, miconazole, or voriconazole (highly potentiating antimicrobials, or HPAs) between September 1 and December 31, 2011, were compared with patients on long-term warfarin therapy who did not receive any antimicrobial during the same period. A multidisciplinary team of physicians, pharmacists, and a systems analyst was then formed to complete a step-by-step outline of the processes involved in warfarin management and concomitant HPA therapy, followed by an FMEA.

Results: Patients taking trimethoprim-sulfamethoxazole, metronidazole, or fluconazole demonstrated a significantly increased risk of having an INR of >4.5. The FMEA identified 134 failure modes. The most common failure modes were as follows: (1) electronic medical records did not identify all patients receiving warfarin, (2) HPA prescribers were unaware of recommended warfarin therapy when HPAs were prescribed, (3) HPA prescribers were unaware that a patient was taking warfarin and that the drug interaction is significant, and (4) warfarin managers were unaware that an HPA had been prescribed for a patient.

Conclusion: An FMEA determined that the risk of adverse events caused by concomitantly administering warfarin and HPAs can be decreased by preemptively identifying patients receiving warfarin, having a care process in place, alerting providers about the patient's risk status, and notifying providers at the anticoagulation clinic.