title: The Annual September Peak in Asthma Exacerbation Rates. Still a Reality?
abstract: BACKGROUND
  Recent research suggests that the asthma epidemic observed in the 1980s and 1990s has stabilized. Changing trends in asthma may have an impact on the well-reported global phenomenon of the "asthma September peak." The 38th week of the year has been identified as the peak time for asthma exacerbations among children.
  
  
  OBJECTIVE
  The purposes of this study were to examine the longitudinal trend of the September peak and to see if it changed over time, differed by age groups, or varied across different geographical regions.
  
  
  METHODS
  Monthly rates of asthma emergency department (ED) and physician outpatient visits were calculated using data provided by the Ontario Asthma Surveillance Information System from 2003 to 2013 for patients of all ages. The Ontario Asthma Surveillance Information System is a population-based surveillance system with over 2 million individuals with asthma. Age-specific rates were calculated using the prevalent asthma population-asthma individuals with at least one health service claim for asthma in the respective year-as the denominator. Rates were stratified by age group and region of residence. Spatial relationships within the province were tested to examine if the September peak was more prominent in certain regions of Ontario.
  
  
  RESULTS
  The highest September peak in ED visits was observed in 2005 for children aged 0-4 years and 5-9 years (18.35 and 8.11 per 1,000 asthma prevalence, respectively). The rate of asthma ED visits of all children was consistently highest in September; however, the spike became marginally less pronounced over time. Since 2005, there has been a 51.7% decrease in the September asthma ED visit rate for all age groups. Monthly physician visits for all age groups usually peaked in October, roughly 4 weeks following the peak in ED visits. Analysis by residence showed that rates throughout Ontario were higher in September than in other months, suggesting that the spike was widespread rather than localized.
  
  
  CONCLUSIONS
  While the magnitude of the September peak has decreased over time, the asthma ED visit rate remains significantly higher in September than in other months. Physician visits are also highest in the fall. These findings stress the importance of empowering children and families to maintain good asthma control throughout the year, including hand washing, to minimize respiratory viral infections in September.
authors.affiliation: 1 Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada.|2 Department of Geography and Planning.|3 Institute of Health Policy, Management and Evaluation, and.
authors.forename: Kristian
authors.initials: K
authors.lastname: Larsen
authors.affiliation: 1 Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada.|4 Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada; and.
authors.forename: Jingqin
authors.initials: J
authors.lastname: Zhu
authors.affiliation: 1 Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada.|5 Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Laura Y
authors.initials: LY
authors.lastname: Feldman
authors.affiliation: 1 Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Simatovic
authors.affiliation: 1 Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada.|3 Institute of Health Policy, Management and Evaluation, and.
authors.forename: Sharon
authors.initials: S
authors.lastname: Dell
authors.affiliation: 1 Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada.|3 Institute of Health Policy, Management and Evaluation, and.|4 Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada; and.|6 Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors.forename: Andrea S
authors.initials: AS
authors.lastname: Gershon
authors.affiliation: 1 Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada.|3 Institute of Health Policy, Management and Evaluation, and.|5 Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.|4 Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada; and.
authors.forename: Teresa
authors.initials: T
authors.lastname: To
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000553:Ambulatory Care / Q000706:statistics & numerical data*; D001249:Asthma / Q000453:epidemiology* / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D018450:Disease Progression; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D015995:Prevalence; D012621:Seasons; D055815:Young Adult
keywords: September peak; asthma; asthma attacks; emergency department visits; physician visits