title: Seasonality patterns in croup presentations to emergency departments in Alberta, Canada: a time series analysis.
abstract: BACKGROUND
  Croup is a common pediatric respiratory illness presenting to the emergency department (ED) in the fall and winter months. Most cases are caused by parainfluenza viruses. We examine the monthly patterns of young children who made croup-related visits to EDs in Alberta, Canada.
  
  
  METHODS
  Emergency department visits were identified in provincial administrative databases to obtain all ED encounters for croup made by young children (aged ≤2 years) during 6 years (April 1, 1999, to March 30, 2005). Time series models (seasonal autoregressive integrated moving average) were developed to capture temporal and seasonal trends and predict future presentations.
  
  
  RESULTS
  Overall, 27,355 croup-related ED visits were made during the study period. More males (62%) than females presented, and most (43%) were younger than 1 year. Differences were observed in the number of visits made in odd and even years. Peak visits occurred in November for odd years and in February for other years. Strong seasonal patterns at 12 months were detected and included in the modeling.
  
  
  CONCLUSIONS
  We observed the presence of a clear biennial pattern of croup ED visits. The seasonal autoregressive moving average models and predictions offer insights into the epidemiology of croup-related visits to EDs and may be helpful in planning both research and resource needs.
authors.affiliation: Department of Pediatrics, niversity of Alberta, 9423 Aberhart Centre, 11402 University Ave NW, Edmonton, Alberta, Canada T6G 2J3. rhonda.rosychuk@ualberta.ca
authors.forename: Rhonda J
authors.initials: RJ
authors.lastname: Rosychuk
authors.forename: Terry P
authors.initials: TP
authors.lastname: Klassen
authors.forename: Donald C
authors.initials: DC
authors.lastname: Voaklander
authors.forename: Ambikaipakan
authors.initials: A
authors.lastname: Senthilselvan
authors.forename: Brian H
authors.initials: BH
authors.lastname: Rowe
mesh_terms: D000416:Alberta; D003440:Croup / Q000453:epidemiology*; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D012621:Seasons; D013997:Time Factors