Evaluation of a pharmacy-managed warfarin-monitoring service to coordinate inpatient and outpatient therapy

Abstract

The effects of implementing a warfarin-monitoring service for inpatients were evaluated. The pharmacy-managed service includes chart review, laboratory interpretation, recommendations for warfarin dosage adjustments, physician and patient education, and coordination of follow-up in the outpatient anticoagulation clinic. In a before-after trial, 52 patients monitored by the warfarin-monitoring service were compared with 97 patients who received warfarin before the service was implemented. Significantly fewer determinations of prothrombin time (PT) and partial thromboplastin time (PTT) were ordered for after-trial patients compared with before-trial patients. PT stability at hospital discharge was significantly improved in after-trial patients. After-trial patients were 12.2 times more likely to be referred to the anticoagulation clinic. No difference was found between the before and after groups in overall compliance with follow-up; however, among patients with no history of substance abuse, after-trial patients were 6.7 times more likely to be compliant. The warfarin-monitoring service had no significant effect on the number of hospital visits and readmissions related to toxicity and recurrence of thrombosis. After-trial patients were 5.4 times more likely to have a therapeutic PT at the initial follow-up appointment. The warfarin-monitoring service improved warfarin dose determination, improved PT stability, and increased referrals to the anticoagulation clinic; among patients with no history of substance abuse, it also improved clinic compliance.