title: Risk stratification schemes, anticoagulation use and outcomes: the risk--treatment paradox in patients with newly diagnosed non-valvular atrial fibrillation.
abstract: OBJECTIVE
  To examine whether warfarin use and outcomes differ across CHADS(2) and CHA(2)DS(2)-VASc risk strata for non-valvular atrial fibrillation (NVAF).
  
  
  METHODS
  Population-based cohort study using linked administrative databases in Alberta, Canada.
  
  
  METHODS
  Inpatient and outpatient.
  
  
  METHODS
  42,834 consecutive patients ≥ 20 years of age with newly diagnosed NVAF.
  
  
  METHODS
  Cerebrovascular events and/or mortality in the first year after diagnosis.
  
  
  RESULTS
  Of 42,834 NVAF patients, 22.7% were low risk on the CHADS(2) risk score (0), 27.5% were intermediate risk (1), and 49.8% were high risk (≥ 2). The CHA(2)DS(2)-VASc risk score reclassified 16,722 patients such that 7.8% were defined low risk, 13.8% intermediate risk and 78.4% high risk. Of the elderly cohort (≥ 65 years) with definite NVAF visits (at least two encounters 30 days apart, n = 8780), 49% were taking warfarin within 90 days of diagnosis. Warfarin use did not differ across risk strata using either the CHADS(2) (p for trend = 0.85) or CHA(2)DS(2)-VASC (p = 0.35). In multivariable adjusted analyses, warfarin use was associated with substantially lower rates of death or cerebrovascular events for patients with CHADS(2) scores of 1 (OR 0.52, 95% CI 0.41 to 0.67) or ≥ 2 (OR 0.61, 95% CI 0.53 to 0.71), or CHA(2)DS(2)-VASc scores of ≥ 2 (OR 0.60, 95% CI 0.53 to 0.68).
  
  
  CONCLUSIONS
  In elderly patients with NVAF and elevated CHADS(2) or CHA(2)DS(2)-VASC scores, warfarin users exhibited lower rates of cerebrovascular events and mortality. However, warfarin use did not differ across risk strata, another example of the risk--treatment paradox in cardiovascular disease.
authors.affiliation: Department of Cardiology, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada. rsandhu2@ualberta.ca
authors.forename: Roopinder K
authors.initials: RK
authors.lastname: Sandhu
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Bakal
authors.forename: Justin A
authors.initials: JA
authors.lastname: Ezekowitz
authors.forename: Finlay A
authors.initials: FA
authors.lastname: McAlister
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000416:Alberta / Q000453:epidemiology; D000925:Anticoagulants / Q000008:administration & dosage*; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000188:drug therapy* / Q000401:mortality; D003937:Diagnosis, Differential; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D015996:Survival Rate / Q000639:trends; D013997:Time Factors
chemical_list: D000925:Anticoagulants