title: Geographic clustering of emergency department presentations for atrial fibrillation and flutter in Alberta, Canada.
abstract: OBJECTIVE
  Atrial fibrillation and flutter (AFF) are the most common arrhythmias seen in the outpatient setting, and they affect more than 300,000 adult Canadians. The aims of this study were to examine temporal and geographic trends in emergency department (ED) presentations made by adults (age ≥ 35 years) for AFF in Alberta, Canada, from 1999 to 2011. Statistical disease cluster detection techniques were used to identify geographic areas with higher numbers of individuals presenting with AFF and higher numbers of ED presentations for AFF than expected by chance alone. Geographic clusters of individuals with stroke or heart failure follow-up within 365 days of ED presentations for AFF were also identified.
  
  
  METHODS
  All ED presentations for AFF made by individuals aged ≥35 years were extracted from Alberta's Ambulatory Care Classification System. The Alberta Health Care Insurance Plan provided population counts and demographics for the patients presenting (age, sex, year, geographic unit). The Physician Claims File provided non-ED physician claims data after a patient's ED presentation. Statistical analyses included numerical and graphical summaries, directly standardized rates, and statistical disease cluster detection tests.
  
  
  RESULTS
  During 12 years, there were 63,395 ED presentations for AFF made by 32,101 individuals. Standardized rates remained relatively stable over time, at about two per 1,000 for individuals presenting to the ED for AFF and about three per 1,000 for ED presentations for AFF. The northern and southeastern parts of the province were identified as clusters of individuals presenting for AFF, and ED presentations for AFF, and several of the areas demonstrated clusters in multiple years. Further, several of the geographic clusters were also identified as potential clusters for stroke or heart failure within 365 days after the ED presentations for AFF.
  
  
  CONCLUSIONS
  This population-based study spanned 12 fiscal years and showed variations in the number of people presenting to EDs for AFF and the number of ED presentations for AFF over geography. The potential clusters identified may represent geographic areas with higher disease severity or a lower availability of non-ED health services. The clusters are not all likely to have occurred by chance, and further investigation and intervention could occur to reduce ED presentations for AFF.
authors.affiliation: The Department of Pediatrics, University of Alberta, Edmonton, Alberta.|Women & Children's Health Research Institute, Edmonton, Alberta.
authors.forename: Rhonda J
authors.initials: RJ
authors.lastname: Rosychuk
authors.affiliation: The Department of Mathematics and Statistics, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.
authors.forename: Hensley H
authors.initials: HH
authors.lastname: Mariathas
authors.affiliation: The Department of Medicine, University of Alberta, Edmonton, Alberta.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Graham
authors.affiliation: The Department of Emergency Medicine, University of Alberta, Edmonton, Alberta.|Alberta Health Services, Edmonton, Alberta, Canada.
authors.forename: Brian R
authors.initials: BR
authors.lastname: Holroyd
authors.affiliation: The Department of Emergency Medicine, University of Alberta, Edmonton, Alberta.|The School of Public Health, University of Alberta, Edmonton, Alberta.|Alberta Health Services, Edmonton, Alberta, Canada.
authors.forename: Brian H
authors.initials: BH
authors.lastname: Rowe
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000416:Alberta; D001281:Atrial Fibrillation / Q000628:therapy*; D001282:Atrial Flutter / Q000628:therapy*; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D062206:Spatial Analysis