Survey of pharmacists' subtherapeutic INR management and anticoagulation bridging practices

Despite extensive warfarin use, optimal management of subtherapeutic international normalized ratios (INRs) remains unclear. This study assessed the differences in bridging practices among pharmacists with varying levels of experience, residency training and prescribing privileges.

An electronic survey was distributed to two ambulatory care pharmacist e-mail lists. Respondents indicated if they would utilize parenteral anticoagulation bridging in 16 clinical scenarios at three therapeutic time points. The scenarios included patients with atrial fibrillation (AFib) (CHADS₂ score of 3-4), AFib (CHADS₂ score of 5-6) and venous thromboembolism (VTE). The AFib time points were as follows: anticoagulation initiation, early phase (<1 month) and maintenance phase (>1 month). VTE time points included early phase (<1 month), months 2-3 and maintenance phase (>3 months).

The survey was completed by 143 respondents. In only three of the scenarios did >50% of respondents indicate they would utilize parenteral anticoagulation bridging. No statistically significant differences in bridging practices were identified between pharmacists providing anticoagulation services in different clinic settings. However, there were significant differences in bridging practices between pharmacists with varying levels of experience, residency training and prescribing privileges in some, but not all of the scenarios.

The standards of care for subtherapeutic INRs warrant further definition.