While percent time within therapeutic range (%TTR) of international normalized ratio of prothrombin time (PT-INR) represents the quality of anticoagulation therapy with warfarin, it is often maintained less than 50% in patients with non-valvular atrial fibrillation (NVAF). We aimed to study if implementation of a multi-disciplinary ambulatory anticoagulation service (MAAS) may improve %TTR. Collaborating with cardiologists at Kanto Rosai Hospital, we conducted a MAAS for NVAF patients receiving warfarin from April 2013 to December 2015. Patients who agreed to utilize the service in addition to their appointments with cardiologists visited pharmacists to have counseling about diet, concomitant medications, and lifestyle. According to a protocol, pharmacists made dose adjustment proposals to cardiologists, if necessary. Upon approval by cardiologists, dose modifications were made. We retrospectively reviewed medical records of the patients who participated in the MAAS before and during the service. The study protocol was approved by the institutional review board. We identified 78 eligible patients (44 males and 34 females, aged 51 to 91 years). Their median %TTR increased significantly (p<0.05) from 57% during the pre-MAAS period to 77% during the MAAS period. In addition, the median percent time below therapeutic range (%TBTR) decreased significantly (p<0.05) from 35% during the baseline period to 11% during the MAAS period. The present study indicates that MAAS improves the quality of anticoagulation therapy with warfarin in ambulatory patients with NVAF. Further prospective, randomized studies with a greater number of patients are required to confirm the results of the present study.
Keywords: multidisciplinary service; non-valvular atrial fibrillation; prothrombin time; time in therapeutic range; warfarin.