title: Quality of anticoagulation monitoring in nonvalvular atrial fibrillation patients: comparison of anticoagulation clinic versus usual care.
abstract: 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.
authors: Department of Clinical Pharmacy and Pharmaceutical Economics & Policy, University of Southern California, Los Angeles, CA 90033, USA. mnichol@usc.edu
authors: Michael B
authors: MB
authors: Nichol
authors: Tara K
authors: TK
authors: Knight
authors: Tom
authors: T
authors: Dow
authors: Gail
authors: G
authors: Wygant
authors: Gerald
authors: G
authors: Borok
authors: Ole
authors: O
authors: Hauch
authors: Richard
authors: R
authors: O'Connor
mesh_terms: 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
chemical_list: D000925:Anticoagulants