Current Trial-Associated Outcomes With Warfarin in Prevention of Stroke in Patients With Nonvalvular Atrial Fibrillation

JAMA Internal Medicine, 04/24/2012

Current use of warfarin as a stroke prevention agent in patients with atrial fibrillation (AF) is associated with a low rate of residual stroke or systemic embolism estimated to be 1.66% per year. Compared with a previous meta–analysis, there has been significant improvement in the proportion of time spent in therapeutic anticoagulation, with a resultant decline in observed stroke rates.

Methods

  • The authors searched the MEDLINE, EMBASE, and Cochrane databases for relevant studies; RCTs comparing warfarin with an alternative thromboprophylaxis strategy with at least 400 patients in the warfarin arm and reporting stroke as an efficacy outcome were included.

Results

  • Eight RCTs with 55 789 patient–years of warfarin therapy follow–up were included.
  • Overall time spent in the therapeutic range was 55% to 68%.
  • The annual incidence of stroke or systemic embolism in patients with AF taking warfarin was estimated to be 1.66% (95% CI, 1.41%–1.91%).
  • Major bleeding rates varied from 1.40% to 3.40% per year across the studies.
  • The risk of stroke per year was significantly higher in elderly patients (2.27%), female patients (2.12%), patients with a history of stroke (2.64%), and patients reporting no previous exposure to vitamin K antagonists (1.96%).
  • There was a significant increase in the annual incidence of stroke with progressively increasing CHADS2 (congestive heart failure, hypertension, age, diabetes, and prior stroke) scores.

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