title: 30-year nationwide trends in incidence of atrial fibrillation in Denmark and associated 5-year risk of heart failure, stroke, and death.
abstract: BACKGROUND
  Long-term nationwide trends in atrial fibrillation (AF) incidence and 5-year outcomes are rare.
  
  
  METHODS
  We conducted a population-based cohort study using the Danish National Patient Registry covering all Danish hospitals. We computed standardized incidence rates during 1983-2012. We used Cox regression to estimate hazard ratios (HRs) of heart failure, stroke, and death within 5years, comparing 5-year calendar periods with the earliest period (1983-1987) as reference.
  
  
  RESULTS
  We identified 312,420 patients with first-time hospital-diagnosed AF. The incidence rate per 100,000person-years increased from 98 in 1983 to 307 in 2012. The mean annual increase during the 30-year study period was 4%, with a 6% increase annually until 2000 and a 1.4% increase annually thereafter. The incidence trends were most pronounced among men and persons above 70years. Among high-risk subgroups, AF incidence was consistently highest in patients with valvular heart disease or heart failure. The rate of heart failure following AF declined by 50% over the entire study period (HR: 0.49, 95% confidence interval (CI): 0.48-0.51) and the mortality rate declined by 40% (HR: 0.62, 95% CI: 0.61-0.63). Within the last two decades, the rate for ischemic stroke declined by 20% (HR 0.81, 95% CI: 0.78-0.84), but increased almost as much for haemorrhagic stroke (HR: 1.14, 95% CI: 1.01-1.29).
  
  
  CONCLUSIONS
  The long-term risk of heart failure, ischemic stroke, and death following onset of AF has decreased remarkably over the last three decades. Still, the threefold increased incidence of hospital-diagnosed AF during the same period is a major public health concern.
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark; Department of Internal Medicine, Regional Hospital of Randers, Denmark. Electronic address: morten.schmidt@clin.au.dk.
authors.forename: Morten
authors.initials: M
authors.lastname: Schmidt
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Sinna Pilgaard
authors.initials: SP
authors.lastname: Ulrichsen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Lars
authors.initials: L
authors.lastname: Pedersen
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Skejby, Aarhus, Denmark.
authors.forename: Hans Erik
authors.initials: HE
authors.lastname: Bøtker
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Skejby, Aarhus, Denmark.
authors.forename: Jens Cosedis
authors.initials: JC
authors.lastname: Nielsen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark; Department of Health Research & Policy (Epidemiology), Stanford University, Stanford, California, USA.
authors.forename: Henrik Toft
authors.initials: HT
authors.lastname: Sørensen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000453:epidemiology* / Q000401:mortality / Q000628:therapy; D015331:Cohort Studies; D003643:Death; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000453:epidemiology* / Q000401:mortality / Q000628:therapy; D006760:Hospitalization / Q000639:trends*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance / Q000379:methods; D012042:Registries; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology* / Q000401:mortality / Q000628:therapy; D013997:Time Factors
keywords: Atrial fibrillation; Atrial flutter; Cohort study; Heart failure; Incidence; Mortality; Stroke