title: Efficacy and safety of apixaban compared with aspirin in the elderly: a subgroup analysis from the AVERROES trial.
abstract: BACKGROUND
  increasing age is associated with a higher prevalence of atrial fibrillation (AF), and higher risks of stroke and bleeding. We report the effects of apixaban versus acetylsalicylic acid (ASA) in older patients (≥75 years and ≥85 years) compared with younger patients with AF unsuitable for vitamin K antagonists.
  
  
  METHODS
  AVERROES (Apixaban Versus ASA to Prevent Stroke In AF Patients Who Have Failed or Are Unsuitable for Vitamin K Antagonist Treatment) trial (n = 5,599) included 1,898 patients ≥75 years and 366 patients ≥85 years. We compared the baseline characteristics and effects of apixaban compared with aspirin on clinical outcomes by age.
  
  
  RESULTS
  compared with aspirin, apixaban was more efficacious for preventing strokes and systemic embolism in patients ≥85 years (absolute rate [AR] 1%/year on apixaban versus 7.5%/year on aspirin; hazard ratio [HR] 0.14, 95% confidence interval [CI] 0.02-0.48) compared with younger patients (AR 1.7%/year on apixaban versus 3.4%/year on aspirin; HR 0.50, 95% CI 0.35-0.69) (P-value for interaction = 0.05). Major haemorrhage was higher in patients ≥85 years compared with younger patients but similar with apixaban versus aspirin in both young and older individuals (4.9%/year versus 1.0%/year on aspirin and 4.7%/year versus 1.2%/year on apixaban) with no significant treatment-by-age interaction (P-value = 0.65).
  
  
  CONCLUSIONS
  older patients with AF are at particularly high risk of stroke if given aspirin and have substantially greater relative and absolute benefits from apixaban compared with younger patients with no greater risk of haemorrhage.
  
  
  BACKGROUND
  ClinicalTrials.gov number: NCT00496769. URL: https://clinicaltrials.gov/ct2/show/NCT00496769.
authors.affiliation: Population Health Research Institute, Hamilton Health Sciences and McMaster University, Hamilton, Canada.
authors.forename: Kuan H
authors.initials: KH
authors.lastname: Ng
authors.affiliation: Population Health Research Institute, Hamilton Health Sciences and McMaster University, Hamilton, Canada.
authors.forename: Olga
authors.initials: O
authors.lastname: Shestakovska
authors.affiliation: Population Health Research Institute, Hamilton Health Sciences and McMaster University, Hamilton, Canada.
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Connolly
authors.affiliation: Population Health Research Institute, Hamilton Health Sciences and McMaster University, Hamilton, Canada.
authors.forename: John W
authors.initials: JW
authors.lastname: Eikelboom
authors.affiliation: Dante Pazzanese Institute of Cardiology, São Paulo, Brazil.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Avezum
authors.affiliation: Estudio Clinicos Latinoamerica, Rosario, Argentina.
authors.forename: Rafael
authors.initials: R
authors.lastname: Diaz
authors.affiliation: Universidad de La Frontera, Temuco, Chile.
authors.forename: Fernando
authors.initials: F
authors.lastname: Lanas
authors.affiliation: Population Health Research Institute, Hamilton Health Sciences and McMaster University, Hamilton, Canada.
authors.forename: Salim
authors.initials: S
authors.lastname: Yusuf
authors.affiliation: Population Health Research Institute, Hamilton Health Sciences and McMaster University, Hamilton, Canada.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Hart
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects / Q000627:therapeutic use*; D001241:Aspirin / Q000009:adverse effects / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000097:blood / Q000150:complications / Q000175:diagnosis / Q000188:drug therapy* / Q000401:mortality; D065427:Factor Xa Inhibitors / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced; D006801:Humans; D008297:Male; D011446:Prospective Studies; D011720:Pyrazoles / Q000009:adverse effects / Q000627:therapeutic use*; D011728:Pyridones / Q000009:adverse effects / Q000627:therapeutic use*; D012307:Risk Factors; D020521:Stroke / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000925:Anticoagulants; D065427:Factor Xa Inhibitors; D011720:Pyrazoles; D011728:Pyridones; C522181:apixaban; D001241:Aspirin
keywords: age; anticoagulation; apixaban; atrial fibrillation; elderly; stroke