Impact of a pharmacist-managed inpatient anticoagulation service for warfarin titration with follow-on care at outpatient anticoagulation clinic

Abstract

Among patients starting warfarin for the first time, daily consultation by a pharmacist has been shown to significantly decrease the length of hospital stay, number of blood tests required, and the number of patients who received excessive anticoagulation therapy. With an anticoagulation service and clinic, there is also continuity of care from inpatient to outpatient. An inpatient anticoagulation service with follow-on care at outpatient anticoagulation clinic was implemented for initiation and titration of warfarin. The pharmacist recommends the daily warfarin dose, the next INR check and monitors the patient till the INR is therapeutic and ready for discharge, then recommends the discharge dose and outpatient appointment date. The patient is then managed at the outpatient anticoagulation clinic. Factors affecting warfarin titration are documented and transferred to the outpatient clinic. The percentage of INR achieving therapeutic range within 5 days was compared for patients initiated on warfarin during the 3 months before implementation and 6 months postimplementation. This was increased from 38% to 87%. Any INR of more than 4 during inpatient stay and subtherapeutic INR on discharge in patients who have had a thromboembolic event were also compared and these were reduced from 30% to near 0%. The average time to therapeutic INR was reduced from 7 to 4 days and average length of stay from 9.7 to 6.5 days. At the outpatient clinic for follow-up management, INR within therapeutic range increased from 38% to 56% and INR within 1.8–4 increased from 64% to 81%. The inpatient anticoagulation service has shown to reduce the length of hospital stay and titration time to therapeutic range, with a reduction in supratherapeutic and subtherapeutic INR. There is also an improvement in the percentage of INR within range at the follow-on outpatient clinic.