Quality of anticoagulation monitoring in nonvalvular atrial fibrillation patients: comparison of anticoagulation clinic versus usual care.
BACKGROUND
Prior research suggests that receiving specialized anticoagulation services enables patients to achieve better clinical outcomes.


OBJECTIVE
To assess the quality of anticoagulation therapy in patients with atrial fibrillation who were enrolled in an anticoagulation clinic (ACC) versus usual care (UC).


METHODS
Using Sharp Rees-Stealy physician group claims data, we estimated time spent in therapeutic range and time to first major bleeding episode or stroke for ACC and UC patients. t-Tests were used to compare time in therapeutic range proportions, and Kaplan-Meier survival analysis was performed to compare rates of bleeding and stroke between groups.


RESULTS
We identified 1107 patients (351 ACC, 756 UC) treated with anticoagulation therapy for atrial fibrillation with more than one international normalized ratio (INR) reported between March 2001 and March 2004. ACC patients spent a greater proportion (68.14%) of time in therapeutic range compared with UC patients (42.07%; p < 0.001). There was a significant difference between groups in average time between INR tests (ACC = 14.31 days, UC = 18.39 days; p < 0.001). ACC patients were 59% less likely to experience a bleed following the index date than were UC patients (HR = 0.41; 95% CI 0.2444 to 0.6999; p = 0.001), but type of care was not a significant predictor for stroke (HR = 0.95; 95% CI 0.5125 to 1.7777; p value NS).


CONCLUSIONS
Results from this observational study reinforce the positive impact that anticoagulation services have on anticoagulation therapy outcomes, emphasizing the importance of providing such services for patients undergoing treatment with warfarin.
Nichol
Michael B
MB
Department of Clinical Pharmacy and Pharmaceutical Economics & Policy, University of Southern California, Los Angeles, CA 90033, USA. mnichol@usc.edu
Knight
Tara K
TK
Dow
Tom
T
Wygant
Gail
G
Borok
Gerald
G
Hauch
Ole
O
O'Connor
Richard
R
D000328:Adult; D000368:Aged; D000554:Ambulatory Care Facilities; D000925:Anticoagulants / Q000009:adverse effects / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy*; D015331:Cohort Studies; D016903:Drug Monitoring / Q000379:methods*; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced; D006801:Humans; D019934:International Normalized Ratio; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011787:Quality of Health Care; D012189:Retrospective Studies; D020521:Stroke / Q000517:prevention & control; D013997:Time Factors; D016896:Treatment Outcome
D000925:Anticoagulants