title: Effect of Adherence to Oral Anticoagulants on Risk of Stroke and Major Bleeding Among Patients With Atrial Fibrillation.
abstract: BACKGROUND
  In comparison to warfarin, non-vitamin K antagonist oral anticoagulants (NOACs) have the advantages of ease of dosing, fewer drug interactions, and lack of need for ongoing monitoring. We sought to evaluate whether these advantages translate to improved adherence and whether adherence is associated with improved outcomes in patients with atrial fibrillation.
  
  
  RESULTS
  We performed a retrospective cohort analysis by using a large US commercial insurance database to identify 64 661 patients with atrial fibrillation who initiated warfarin, dabigatran, rivaroxaban, or apixaban treatment between November 1, 2010, and December 31, 2014. During a median of 1.1 y of follow-up, 47.5% of NOAC patients had a proportion of days covered of ≥80%, compared with 40.2% in warfarin patients (P<0.001). Patients with CHA2DS2-VASc (risk based on the presence of congestive heart failure, hypertension age 65-74 y, age ≥75 y, diabetes mellitus, prior stroke or transient ischemic attack, vascular disease, sex category) score ≥4 were at increased risk of stroke when they were not taking anticoagulation ≥1 month versus <1 week (1-3 months: hazard ratio [HR] 1.96, 3-6 months: HR 2.64, ≥6 months: HR 3.66; all P<0.001). Patients with CHA2DS2-VASc score 2 or 3 were at increased risk of stroke when they were not taking anticoagulation ≥6 months (HR 2.73, P<0.001). In these patients with CHA2DS2-VASc score ≥2, nonadherence was not associated with intracranial hemorrhage. Among patients with CHA2DS2-VASc score 0 or 1, time not taking anticoagulation was not associated with stroke, but not taking anticoagulation ≥3 months was associated with a significant reduction of bleeding.
  
  
  CONCLUSIONS
  Adherence to anticoagulation is poor in practice and may be modestly improved with NOACs. Adherence to therapy appears to be most important in patients with CHA2DS2-VASc score ≥2, whereas the benefits of anticoagulation may not outweigh the harms in patients with CHA2DS2-VASc score 0 or 1.
authors.affiliation: Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery, Mayo Clinic, Rochester, MN yao.xiaoxi@mayo.edu.
authors.forename: Xiaoxi
authors.initials: X
authors.lastname: Yao
authors.affiliation: Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery, Mayo Clinic, Rochester, MN Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Scottsdale, AZ Division of Health Care Policy and Research, Department of Health Services Research, Mayo Clinic, Rochester, MN.
authors.forename: Neena S
authors.initials: NS
authors.lastname: Abraham
authors.affiliation: Division of General Internal Medicine, Johns Hopkins School of Medicine, Baltimore, MD Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health and Center for Drug Safety and Effectiveness, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD.
authors.forename: G Caleb
authors.initials: GC
authors.lastname: Alexander
authors.affiliation: Optum Labs, Cambridge, MA.
authors.forename: William
authors.initials: W
authors.lastname: Crown
authors.affiliation: Division of Health Care Policy and Research, Department of Health Services Research, Mayo Clinic, Rochester, MN.
authors.forename: Victor M
authors.initials: VM
authors.lastname: Montori
authors.affiliation: Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery, Mayo Clinic, Rochester, MN.
authors.forename: Lindsey R
authors.initials: LR
authors.lastname: Sangaralingham
authors.affiliation: Heart Rhythm Section, Cardiovascular Diseases, Mayo Clinic, Rochester, MN.
authors.forename: Bernard J
authors.initials: BJ
authors.lastname: Gersh
authors.affiliation: Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery, Mayo Clinic, Rochester, MN Division of Health Care Policy and Research, Department of Health Services Research, Mayo Clinic, Rochester, MN Optum Labs, Cambridge, MA.
authors.forename: Nilay D
authors.initials: ND
authors.lastname: Shah
authors.affiliation: Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery, Mayo Clinic, Rochester, MN Heart Rhythm Section, Cardiovascular Diseases, Mayo Clinic, Rochester, MN.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Noseworthy
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage* / Q000009:adverse effects*; D001281:Atrial Fibrillation / Q000097:blood / Q000150:complications / Q000175:diagnosis / Q000188:drug therapy*; D001777:Blood Coagulation / Q000187:drug effects*; D016208:Databases, Factual; D004334:Drug Administration Schedule; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced*; D006801:Humans; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D020521:Stroke / Q000097:blood / Q000175:diagnosis / Q000517:prevention & control*; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000925:Anticoagulants
keywords: CHA2DS2‐VASc; adherence; bleeding; non–vitamin K antagonist oral anticoagulants; stroke