title: Revisiting sex differences in outcomes in non-valvular atrial fibrillation: a population-based cohort study.
abstract: OBJECTIVE
  In patients with non-valvular atrial fibrillation (NVAF), it is uncertain whether the higher risk of ischaemic stroke in women reported in some studies is due to residual confounding. We assessed this association using standard time-fixed and more accurate time-dependent adjustment for confounders.
  
  
  RESULTS
  Using the computerized databases of the Régie de l'assurance maladie du Québec (RAMQ), we identified a cohort of patients with NVAF during 2000-2009 and RAMQ medication coverage. Cox proportional hazards models were used to estimate the hazard ratio (HR) of ischaemic stroke, death, and bleeding, associated with sex, adjusting for time-fixed covariates at cohort entry. This was compared with adjustment for time-dependent covariates using an age and time-matched nested case-control analysis. The cohort included 147 622 patients. During a mean follow-up of 2.9 years 11 326 patients had a stroke (incidence rate 2.6 per 100 per year). Using time-fixed adjustment for confounders, women had a moderately higher risk of ischaemic stroke than men (HR 1.16 (Confidence interval (CI) 95% 1.11-1.21). Matching on age and using time-dependent adjustment for confounders, women were not at higher risk of stroke than men (Rate Ratio 1.01; 95% CI 0.97-1.05). Mortality and bleeding rates were lower in women compared with men in both analyses.
  
  
  CONCLUSIONS
  In NVAF, women were not at higher risk of thromboembolic events than men in our study. The small increased risk reported in previous studies may be related to residual confounding, in particular from insufficient control for age.
authors.affiliation: Centre for Clinical Epidemiology, Lady Davis Institute for Medical Research, Jewish General Hospital, 3755 Côte Sainte-Catherine Road, Montreal, QC H3T 1E2, Canada.|Department of Neurology and Neurosurgery, McGill University, 3801 University Street, Montreal QC H3A 2B4, Canada.|Department of Epidemiology, Biostatistics and Occupational Health, McGill University, 1020 Pine Avenue West, Montreal, QC H3A 1A2, Canada.
authors.forename: Christel
authors.initials: C
authors.lastname: Renoux
authors.affiliation: Centre for Clinical Epidemiology, Lady Davis Institute for Medical Research, Jewish General Hospital, 3755 Côte Sainte-Catherine Road, Montreal, QC H3T 1E2, Canada.
authors.forename: Janie
authors.initials: J
authors.lastname: Coulombe
authors.affiliation: Centre for Clinical Epidemiology, Lady Davis Institute for Medical Research, Jewish General Hospital, 3755 Côte Sainte-Catherine Road, Montreal, QC H3T 1E2, Canada.|Department of Epidemiology, Biostatistics and Occupational Health, McGill University, 1020 Pine Avenue West, Montreal, QC H3A 1A2, Canada.
authors.forename: Samy
authors.initials: S
authors.lastname: Suissa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000401:mortality / Q000628:therapy*; D002545:Brain Ischemia / Q000401:mortality; D016022:Case-Control Studies; D005260:Female; D054625:Healthcare Disparities; D006470:Hemorrhage / Q000401:mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011792:Quebec / Q000453:epidemiology; D012307:Risk Factors; D017678:Sex Distribution; D020521:Stroke / Q000401:mortality; D013923:Thromboembolism / Q000401:mortality*; D055815:Young Adult
keywords: Atrial fibrillation ; Epidemiology ; Mortality; Sex ; Stroke 