title: Chronic atrial fibrillation: Incidence, prevalence, and prediction of stroke using the Congestive heart failure, Hypertension, Age >75, Diabetes mellitus, and prior Stroke or transient ischemic attack (CHADS2) risk stratification scheme.
abstract: BACKGROUND
  The aim of the study is to estimate the incidence and prevalence of chronic AF (cAF) in the United Kingdom and test the accuracy of the CHADS2 score for stroke prediction.
  
  
  METHODS
  The General Practice Research Database was used to identify patients aged 40+ years diagnosed with cAF and control patients. Harrell's C-statistic was used to test possible improvements in CHADS2.
  
  
  RESULTS
  The study population included 51,807 cAF patients. The incidence of cAF increased by age and was higher in men than women. The prevalence of cAF has increased over time. The excess 5-year risk for stroke in cAF patients correlated well with CHADS2 as follows: score 0, 1.9% (95% CI 1.6-2.1); 1, 3.0% (95% CI 2.7-3.3); 2, 4.7% (95% CI 4.3-5.1); 3, 7.2% (95% CI 6.6-7.9); 4, 10.5% (95% CI 9.4-11.5); 5, 13.9% (95% CI 12.2-15.5); and 6, 15.8% (95% CI 13.5-18.1). Adding sex, the extension of age categories and reweighing of established risk factors improved CHADS2 accuracy (C-statistic 0.68-0.72). Applying the reclassification resulted in a substantial number of patients changing stroke risk category.
  
  
  CONCLUSIONS
  Atrial fibrillation is a prevalent and growing problem, which significantly increases the risk of ischemic stroke. The CHADS2 score is a good predictor of the stroke risk but could be improved.
authors.affiliation: General Practice Research Database, Medicines and Health Care Products Regulatory Agency, London, United Kingdom.
authors.forename: Stephan
authors.initials: S
authors.lastname: Rietbrock
authors.forename: Emma
authors.initials: E
authors.lastname: Heeley
authors.forename: Jonathan
authors.initials: J
authors.lastname: Plumb
authors.forename: Tjeerd
authors.initials: T
authors.lastname: van Staa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000453:epidemiology*; D016022:Case-Control Studies; D015984:Causality; D002908:Chronic Disease; D015331:Cohort Studies; D015897:Comorbidity; D016001:Confidence Intervals; D003920:Diabetes Mellitus / Q000175:diagnosis / Q000453:epidemiology*; D004562:Electrocardiography; D005260:Female; D015577:Geriatric Assessment; D006305:Health Status Indicators; D006333:Heart Failure / Q000175:diagnosis / Q000453:epidemiology*; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000453:epidemiology*; D015994:Incidence; D002546:Ischemic Attack, Transient / Q000175:diagnosis / Q000453:epidemiology; D008297:Male; D011237:Predictive Value of Tests; D015995:Prevalence; D012042:Registries; D018570:Risk Assessment / Q000379:methods*; D012680:Sensitivity and Specificity; D020521:Stroke / Q000175:diagnosis / Q000453:epidemiology*; D016019:Survival Analysis; D006113:United Kingdom / Q000453:epidemiology