title: Are there seasonal patterns to ruptured aortic aneurysms and dissections of the aorta?
abstract: OBJECTIVE
  to test the hypothesis that there are seasonal increases in aortic aneurysm ruptures and dissections.
  
  
  METHODS
  a retrospective, population-based time series analysis of hospital admissions for dissection and rupture of the aortic aneurysm in the Province of Ontario from 1988-1997. Analyses were carried out on weekly and monthly aggregations of hospital admissions.
  
  
  RESULTS
  there is weak statistical evidence of seasonality in the weekly time series (BKS=0.0987, p=0.03) and no evidence of seasonality in the monthly time series. There is no evident seasonality in the time plots. The incidence of dissections increased significantly over the study period while the incidence of ruptures decreased.
  
  
  CONCLUSIONS
  this large population-based study, contrary to other published reports, fails to find convincing evidence of seasonality in rupture or dissection of aortic aneurysm though did demonstrate contrasting trends in incidence.
authors.affiliation: Primary Care Research Unit, Sunnybrook and Women's College Health Sciences Centre, Toronto, Canada.
authors.forename: R E
authors.initials: RE
authors.lastname: Upshur
authors.forename: M M
authors.initials: MM
authors.lastname: Mamdani
authors.forename: K
authors.initials: K
authors.lastname: Knight
mesh_terms: D000784:Aortic Dissection / Q000453:epidemiology* / Q000209:etiology; D001014:Aortic Aneurysm / Q000453:epidemiology* / Q000209:etiology; D001019:Aortic Rupture / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D015233:Models, Statistical; D009864:Ontario / Q000453:epidemiology; D010343:Patient Admission / Q000706:statistics & numerical data* / Q000639:trends; D011159:Population Surveillance; D012189:Retrospective Studies; D012307:Risk Factors; D012621:Seasons; D013997:Time Factors