Dabigatran and warfarin for secondary prevention of stroke in atrial fibrillation patients: a nationwide cohort study

Am J Med. 2014 Dec;127(12):1172-8.e5. doi: 10.1016/j.amjmed.2014.07.023. Epub 2014 Sep 1.


Background: This register-based observational study compares dabigatran to warfarin for secondary stroke prevention in atrial fibrillation patients among both "new starters" on dabigatran and "switchers" to dabigatran from warfarin.

Methods: We identified, in nationwide Danish registries, 2398 patients with atrial fibrillation and a history of stroke/transient ischemic attack, making a first-time purchase of dabigatran 110 mg twice a day (bid; D110) and 150 mg bid (D150). Patients were categorized as either vitamin K antagonist (VKA) naive or experienced. Warfarin controls were identified using a complete (for VKA-naive dabigatran patients) or matched sampling approach (for VKA-experienced dabigatran patients). Subjects were followed for an average of 12.6 months for stroke and transient ischemic attacks. Confounder-adjusted Cox regression models were used to compare event rates between treatments.

Results: Among patients with a history of stroke/transient ischemic attack and prior VKA experience, switching to dabigatran was associated with an increased stroke/transient ischemic attack rate for both dabigatran doses compared with continuing on warfarin (D110 hazard ratio [HR] 1.99; 95% confidence interval [CI], 1.42-2.78; D150 HR 2.34; 95% CI, 1.60-3.41). Among prior stroke/transient ischemic attack patients who were new starters on dabigatran or warfarin, the rate of stroke/transient ischemic attack for both doses of dabigatran was similar to or lower than warfarin (D110 HR 0.64; 95% CI, 0.50-0.80; D150 HR 0.92l; 95% CI, 0.73-1.15).

Conclusions: In this register-based study, VKA-experienced patients with a history of stroke or transient ischemic attack who switched to dabigatran therapy had an increased rate of stroke compared with patients persisting with warfarin therapy.

Keywords: Antithrombotic therapy; Atrial fibrillation; Comparative effectiveness; Dabigatran; Stroke; Warfarin.

Publication types

  • Comparative Study
  • Observational Study

MeSH terms

  • Aged
  • Aged, 80 and over
  • Anticoagulants / therapeutic use
  • Antithrombins / therapeutic use*
  • Atrial Fibrillation / complications
  • Atrial Fibrillation / drug therapy*
  • Benzimidazoles / therapeutic use*
  • Cohort Studies
  • Dabigatran
  • Denmark
  • Female
  • Humans
  • Ischemic Attack, Transient / prevention & control*
  • Male
  • Middle Aged
  • Proportional Hazards Models
  • Registries*
  • Secondary Prevention / methods
  • Stroke / etiology
  • Stroke / prevention & control*
  • Treatment Outcome
  • Warfarin / therapeutic use*
  • beta-Alanine / analogs & derivatives*
  • beta-Alanine / therapeutic use


  • Anticoagulants
  • Antithrombins
  • Benzimidazoles
  • beta-Alanine
  • Warfarin
  • Dabigatran