Apixaban 5 and 2.5 mg twice-daily versus warfarin for stroke prevention in nonvalvular atrial fibrillation patients: Comparative effectiveness and safety evaluated using a propensity-score-matched approach

PLoS One. 2018 Jan 26;13(1):e0191722. doi: 10.1371/journal.pone.0191722. eCollection 2018.


Prior real-world studies have shown that apixaban is associated with a reduced risk of stroke/systemic embolism (stroke/SE) and major bleeding versus warfarin. However, few studies evaluated the effectiveness and safety of apixaban according to its dosage, and most studies contained limited numbers of patients prescribed 2.5 mg twice-daily (BID) apixaban. Using pooled data from 4 American claims database sources, baseline characteristics and outcomes for patients prescribed 5 mg BID and 2.5 mg BID apixaban versus warfarin were compared. After 1:1 propensity-score matching, 31,827 5 mg BID apixaban-matched warfarin patients and 6600 2.5 mg BID apixaban-matched warfarin patients were identified. Patients prescribed 2.5 mg BID apixaban were older, had clinically more severe comorbidities, and were more likely to have a history of stroke and bleeding compared with 5 mg BID apixaban patients. Compared with warfarin, 5 mg BID apixaban was associated with a lower risk of stroke/SE (hazard ratio [HR]: 0.70, 95% confidence interval [CI]: 0.60-0.81) and major bleeding (HR: 0.59, 95% CI: 0.53-0.66). Compared with warfarin, 2.5 mg BID apixaban was also associated with a lower risk of stroke/SE (HR: 0.63, 95% CI: 0.49-0.81) and major bleeding (HR: 0.59, 95% CI: 0.49-0.71). In this real-world study, both apixaban doses were assessed in 2 patient groups differing in age and clinical characteristics. Each apixaban dose was associated with a lower risk of stroke/SE and major bleeding compared with warfarin in the distinct population for which it is being prescribed in United States clinical practice.

Trial registration: Clinicaltrials.Gov Identifier: NCT03087487.

Publication types

  • Comparative Study
  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Atrial Fibrillation / complications*
  • Drug Administration Schedule
  • Female
  • Humans
  • Male
  • Middle Aged
  • Pyrazoles / administration & dosage*
  • Pyridones / administration & dosage*
  • Retrospective Studies
  • Stroke / etiology
  • Stroke / prevention & control*
  • Warfarin / administration & dosage*
  • Young Adult


  • Pyrazoles
  • Pyridones
  • apixaban
  • Warfarin

Associated data

  • ClinicalTrials.gov/NCT03087487

Grants and funding

This study was funded by Bristol-Myers Squibb and Pfizer. Specifically, Chris Haddlesey and Neel Vaidya of STATinMED provided medical writing and editorial support. Additional medical writing and editorial support was provided by Jacob Willet of Oxford PharmaGenesis. Statistical programming for this study was provided by Juan Du of STATinMED Research and funded by Bristol-Myers Squibb and Pfizer. The funder provided support in the form of salaries for authors XL, MH, KG, KF, AN, XP, AK, XL, JM, SD, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.