Clinical and economic impacts of a pharmacist-managed anticoagulation clinic

This study evaluated the impact of a pharmacist-managed anticoagulation clinic (AC) on the clinical and economic outcomes of patient newly treated with warfarin therapy. A retrospective chart review was conducted for patients initiating warfarin therapy between November 1997 and April 1998. Patients were maintained on warfarin therapy for a minimum of two months. Patients were followed for either one-year postinitiation of warfarin usage or until discontinuation of warfarin therapy, whichever occurred earlier. Data were analyzed for 65 AC and 99 usual care (UC) patients. Anticoagulation clinic patients had a greater proportion of international normalized ratio (INR) values that were within therapeutic range than UC patients (61.3% and 56.9% of INR values, respectively) and a greater number of days with INR values in therapeutic range than UC patients (56.2% of days for AC patients and 48.8% of days for UC patients). The incidence rates of warfarin-related events were similar in both groups. Total charges for all health care services during the follow-up period were 50 percent greater for UC patients than for AC patients ($2,012.97 and $952.65 per UC and AC patient-month, respectively; p<0.05). Despite a higher mean number of days hospitalized per patientmonth for AC patients for warfarin-related events, charges for warfarin-related inpatient admissions were lower for AC patients than UC patients ($239 per patient-month for the AC group and $370 per patient-month for the UC group). Charges for non-warfarinrelated inpatient admissions and the mean incidence rates for non-warfarin-related hospitalizations and outpatient visits were also less for AC patients than UC patients. Usual care patients were more than twice as likely as AC patients to be prescribed a medication that could potentially interact with warfarin therapy. The rates of adherence to warfarin therapy, as measured by the medication possession ratio, were similar for both groups. Anticoagulation clinic patients experienced better anticoagulation control, incurred fewer overall charges for warfarin-related and non-warfarin-related health care services, and were less likely to experience drug interactions with warfarin therapy than UC patients.