Impact of a pharmacist-driven warfarin management protocol on achieving therapeutic International Normalized Ratios

Warfarin is a high alert medication and a challenge to dose and monitor. Pharmacist-driven warfarin management has been shown to decrease the time international normalized ratio (INR) is out of range, which may reduce undesired outcomes. The purpose of this study is to assess the effect of the implementation of a pharmacist-driven warfarin management protocol on the achievement of therapeutic INRs.

A warfarin management protocol was developed using evidence based literature and similar protocols from other institutions. Pharmacists utilized the protocol to provide patient specific warfarin dosing upon provider referral. To evaluate the protocol's impact, a retrospective chart review pre- and post-implementation was completed for admitted patients receiving warfarin.

Three hundred twenty-seven charts were reviewed for pre- and post-implementation data. INRs within therapeutic range increased from 27.8% before protocol implementation to 38.5% after implementation. There was also a reduction in subtherapeutic INRs (55.3% pre to 39% post) and supratherapeutic INRs 5 or above (3.7% pre to 2.6% post). Supratherapeutic INRs between 3 and 5 did increase from 13.2% before protocol implementation to 19.9% in the pharmacist managed group. In addition to reducing the time to achievement of therapeutic INRs by 0.5 days, implementation of the protocol resulted in an increased the number of patients with at least one therapeutic INR during admission (35% pre to 40% post).

The implementation of a pharmacist-driven warfarin dosing protocol increased therapeutic INRs, and decreased the time to therapeutic range, as well as the proportion of subtherapeutic INRs and supratherapeutic INRs 5 or greater. Additional benefits of the protocol include documentation of Joint Commission National Patient Safety Goal compliance, promotion of interdisciplinary collaboration and increased continuity of care.