Inpatient warfarin management: pharmacist management using a detailed dosing protocol

Abstract

Hospitalized patients receiving anticoagulants such as warfarin are at increased risk for adverse events because of difficulties maintaining a therapeutic international normalized ratio (INR). We sought to determine whether a detailed warfarin dosing protocol administered by pharmacists with minimal physician oversight significantly reduced the proportion of hospitalized patients with a supratherapeutic INR. We conducted a prospective, nonrandomized trial with patients on cardiology, internal medicine, and family medicine inpatient services who received at least 1 dose of warfarin while hospitalized. The baseline group included 293 patients, and the intervention group comprised 217 patients. Baseline characteristics were similar in each group, except that more patients received antibiotics in the intervention group. The defect rate (INR > 5 after receiving warfarin) in the baseline group was significantly higher than in the intervention group (7.85 vs. 1.85%). Conversely, the percentage of patients with an INR less than 1.7 after 4 warfarin doses was lower in the intervention patients, indicating overall improvement in therapeutic levels. Dosing discussions were required between the pharmacist and a physician for only 6% of intervention patients. The protocol effectively reduced overanticoagulation without increasing under anticoagulation during hospitalization and reduced the need for close physician oversight.