Quality of anticoagulation control and costs of monitoring warfarin therapy among patients with atrial fibrillation in clinic settings: a multi-site managed-care study.
BACKGROUND
Warfarin is recommended for prevention of stroke in patients with atrial fibrillation who are at moderate or high risk, but requires intensive management to achieve safe and optimal anticoagulation control. Anticoagulation clinics are often used to administer warfarin therapy more effectively.


OBJECTIVE
To collect data from multiple sites and assess the quality and costs associated with anticoagulation clinic services.


METHODS
A random sample of 600 adults with chronic nonvalvular atrial fibrillation (CNVAF) receiving warfarin was selected from anticoagulation clinics affiliated with 3 health plans. Patients were identified between 1996 and 1998 and followed for up to one year. We assessed the proportion of time that international normalized ratio (INR) values were within the recommended range (2.0-3.0) and the costs of anticoagulation clinic care.


RESULTS
Patients had an average of 18 clinic contacts over a mean duration of follow-up of 10.5 months. On average, patients were within the recommended INR range 62% of this time, with 25% of days below range and 13% above range. The mean per-patient cost of warfarin monitoring over the follow-up period averaged $261 at site A, $305 at site B, and $205 at site C (in 2003 US$). Mean costs for patients treated for one full year were $288, $339, and $216, respectively.


CONCLUSIONS
In 3 geographically diverse health plans, anticoagulation clinics provided a generally higher quality of control than previously reported in other observational studies. This study highlights the costs of obtaining this level of control.
Menzin
Joseph
J
Boston Health Economics, 20 Fox Road, Waltham, MA 02451-1007, USA. jmenzin@bhei.com
Boulanger
Luke
L
Hauch
Ole
O
Friedman
Mark
M
Marple
Cheryl Beadle
CB
Wygant
Gail
G
Hurley
Judith S
JS
Pezzella
Stephen
S
Kaatz
Scott
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000554:Ambulatory Care Facilities; D000925:Anticoagulants / Q000191:economics* / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000188:drug therapy / Q000191:economics*; D015331:Cohort Studies; D016903:Drug Monitoring; D005260:Female; D017048:Health Care Costs; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008329:Managed Care Programs; D008875:Middle Aged; D011785:Quality Assurance, Health Care; D012189:Retrospective Studies; D014859:Warfarin / Q000191:economics* / Q000627:therapeutic use
D000925:Anticoagulants; D014859:Warfarin