Optimization of Inpatient Warfarin Therapy: Impact of Daily Consultation by a Pharmacist-Managed Anticoagulation Service

Abstract

Spanish

French

OBJECTIVE:

To determine the effect of daily consultation by a team of hospital pharmacists on the accuracy and rapidity of optimizing warfarin therapy.

DESIGN:

Comparison of a historical control cohort with a prospective cohort matched for treatment indication.

SETTING:

A 400-bed university teaching hospital.

PATIENTS:

Sixty consecutive patients hospitalized in 1992 and starting warfarin for the first time, with anticoagulation therapy managed by physicians, were compared with 60 patients matched for warfarin indication hospitalized in 1995, but with anticoagulation therapy managed with pharmacy consultation.

RESULTS:

Pharmacist management of initial warfarin therapy resulted in a significant reduction in the length of hospitalization compared with physician dosing, from 9.5 ± 5.6 days to 6.8 ± 4.4 days (p = 0.009). The number of patients and patient-days with international normalized ratio (INR) values >3.5 were reduced by pharmacist dosing from 37 patients and 142 days to 16 patients and 29 days, respectively (p < 0.001). Similarly, the number of patients and patient-days with INR >6.0 were reduced from 20 patients and 50 days to two patients and six days, respectively (p < 0.001). There were six documented bleeding complications in 1992 compared with one in 1995 (p = 0.11). The mean INR at discharge was significantly lower in the pharmacy surveillance group, 2.6 ± 0.58, compared with the physician cohort, 3.3 ± 2.1 (p = 0.07). Readmissions after discharge due to bleeding or recurrent thrombosis were reduced from five (at 1 mo) and 10 (at 3 mo) to two and five readmissions, respectively, by pharmacist intervention (p = 0.43). The number of patients with concurrently prescribed drugs known to significantly interact with warfarin was significantly lower (6 vs. 13; p = 0.02) in the pharmacy surveillance group.

CONCLUSIONS:

Among patients starting warfarin for the first time, daily consultation by a pharmacist significantly decreased the length of hospital stay and the number of patients who received excessive anticoagulation therapy. These findings translate into improved quality of care and potentially significant cost savings.

Keywords

warfarin anticoagulation service

Get full access to this article

View all access options for this article.

References

Hirsh

Dalen

Anderson

Poller

Bussey

Ansel

Oral anticoagulants: Mechanism of action, clinical effectiveness, and optimal therapeutic range. Chest 1998;114(suppl):445S–69S.

Harrison

Johnston

ART

Massicotte

Crowther

Moffat

Hirsh

. Comparison of 5-mg and 10-mg loading doses in initiation of warfarin therapy. Ann Intern Med 1997;126:133–6.

Barr

Schumacher

. Outcomes assessments of therapeutic drug monitoring: System and patient considerations. In: Schumacher

, ed. Therapeutic drug monitoring. 1st ed. Norwalk, CT: Appleton & Lange, 1995:191–236.

Pawloski

Kersh

. Therapeutic heparin monitoring service in a small community hospital. Hosp Pharm 1992;27:703–6,723.

Wilt

Gums

Ahmed

Moore

. Outcome analysis of a pharmacist-managed anticoagulation service. Pharmacotherapy 1995;15: 732–9.

Gray

Garabedian-Ruffalo

Chretien

. Cost-justification of a clinical pharmacist-managed anticoagulation clinic. Drug Intell Clin Pharm 1985;19:575–80.

Garabedian-Ruffalo

Gray

Sax

Ruffalo

. Retrospective evaluation of a pharmacist-managed warfarin anticoagulation clinic. Am J Hosp Pharm 1985;42:304–8.

Conte

Kehoe

Nielson

Lodhia

. Nine-year experience with a pharmacist-managed anticoagulation clinic. Am J Hosp Pharm 1986;43:2460–3.

Eliza

Pearson

. Implementation and evaluation of a pharmacist-assisted warfarin dosing program. Can J Hosp Pharm 1977;50:169–75.

10.

Hull

Hirsh

Jay

Carter

England

Gent

Different intensities of oral anticoagulation therapy in the treatment of proximal-vein thrombosis. N Engl J Med 1982;307:1676–81.

11.

Hull

Delmore

Carter

Hirsh

Genton

Gent

Adjusted subcutaneous heparin versus warfarin sodium in the long-term treatment of venous thrombosis. N Engl J Med 1982;306:189–94.

12.

Altman

Rouvier

Garfinkel

D'Ortencio

Manzanel

de La Fuente

Comparison of two levels of anticoagulant therapy in patients with substitute heart valves. J Thorac Cardiovasc Surg 1991;101: 427–31.

13.

Fihn

McDonnel

Martin

Henikoff

Vermes

Kent

Risk factors for complications of chronic anticoagulation: A multicenter study. Ann Intern Med 1993;118:511–20.

14.

Landefeld

Goldman

. Major bleeding in outpatients treated with warfarin: Incidence and prediction by factors known at the start of outpatient therapy. Am J Med 1989;87:144–52.

15.

Petitte

Strom

Melmon

. Duration of warfarin anticoagulation therapy and the probabilities of recurrent thromboembolism and hemorrhage. Am J Med 1986;81:255–9.

16.

King

Dager

Branch

White

Hutchinson

Sauer

. Initial results of a multidisciplinary university hospital anticoagulation service managing home treatment of deep vein thrombosis with enoxaparin (abstract). J Thrombosis Thrombolysis 1998;5(suppl):S75.