Examining Warfarin Dosing Decisions to Improve Anticoagulation Management

Abstract

Background: Adherence to relatively simple warfarin dosing algorithms has been found to be effective for improving anticoagulation control, and in turn for reducing adverse events. Achieving consistent use of such algorithms by clinicians managing the care is a known challenge. Objective: To examine warfarin management patterns at anticoagulation clinics in light of algorithm-recommended management and to develop a methodology for quality assurance around this issue. Methods: We reviewed 2711 postappointment clinician notes between October 1, 2011, and March 31, 2012, for 481 patients across 5 Veterans Health Administration (VA) sites. Key data gathered were of dosing decisions made following the latest available international normalized ratio (INR). Results: Dosing decisions discordant with algorithm recommendations were made at 45% of all the appointments studied; most (78%) followed an out-of-range INR value, as opposed to an in-range value. We found “signatures of care” at each site, characterized by consistent patterns of concordant and discordant management. For example, some sites were more discordant in terms of one-time dose changes (eg, take an extra dose for 1 day), while others were more discordant regarding follow-up intervals, and still others regarding the extent of weekly dose changes (usually larger than recommended). It was also not uncommon to change the dose following an in-range value (not recommended). Conclusions: We identified 5 distinct patterns of management across 5 sites; none were particularly adherent to clinical guidelines. Our method is a suitable basis for audit and feedback to help sites improve patient outcomes by practicing in a more guideline-concordant manner.