title: Simplicity within complexity: seasonality and predictability of hospital admissions in the province of Ontario 1988-2001, a population-based analysis.
abstract: BACKGROUND
  Seasonality is a common feature of communicable diseases. Less well understood is whether seasonal patterns occur for non-communicable diseases. The overall effect of seasonal fluctuations on hospital admissions has not been systematically evaluated.
  
  
  METHODS
  This study employed time series methods on a population based retrospective cohort of for the fifty two most common causes of hospital admissions in the province of Ontario from 1988-2001. Seasonal patterns were assessed by spectral analysis and autoregressive methods. Predictive models were fit with regression techniques.
  
  
  RESULTS
  The results show that 33 of the 52 most common admission diagnoses are moderately or strongly seasonal in occurrence; 96.5% of the predicted values were within the 95% confidence interval, with 37 series having all values within the 95% confidence interval.
  
  
  CONCLUSIONS
  The study shows that hospital admissions have systematic patterns that can be understood and predicted with reasonable accuracy. These findings have implications for understanding disease etiology and health care policy and planning.
authors.affiliation: Department of Family and Community Medicine, University of Toronto, 263 McCaul Street, Toronto, ON M5T 1W7, Canada. rupshur@idirect.com
authors.forename: Ross E G
authors.initials: RE
authors.lastname: Upshur
authors.forename: Rahim
authors.initials: R
authors.lastname: Moineddin
authors.forename: Eric
authors.initials: E
authors.lastname: Crighton
authors.forename: Lori
authors.initials: L
authors.lastname: Kiefer
authors.forename: Muhammad
authors.initials: M
authors.lastname: Mamdani
mesh_terms: D000208:Acute Disease / Q000453:epidemiology; D001988:Bronchiolitis / Q000453:epidemiology; D002908:Chronic Disease / Q000453:epidemiology; D003141:Communicable Diseases / Q000453:epidemiology; D003324:Coronary Artery Disease / Q000453:epidemiology; D003681:Dehydration / Q000453:epidemiology; D005544:Forecasting; D006301:Health Services Needs and Demand / Q000706:statistics & numerical data / Q000639:trends*; D006761:Hospitals / Q000706:statistics & numerical data*; D006801:Humans; D009864:Ontario / Q000453:epidemiology; D010343:Patient Admission / Q000706:statistics & numerical data / Q000639:trends*; D011159:Population Surveillance / Q000379:methods; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology; D012189:Retrospective Studies; D012621:Seasons; D013997:Time Factors; D014600:Utilization Review / Q000379:methods*