title: Emergency department visits, ambulance calls, and mortality associated with an exceptional heat wave in Sydney, Australia, 2011: a time-series analysis.
abstract: BACKGROUND
  From January 30-February 6, 2011, New South Wales was affected by an exceptional heat wave, which broke numerous records. Near real-time Emergency Department (ED) and ambulance surveillance allowed rapid detection of an increase in the number of heat-related ED visits and ambulance calls during this period. The purpose of this study was to quantify the excess heat-related and all-cause ED visits and ambulance calls, and excess all-cause mortality, associated with the heat wave.
  
  
  METHODS
  ED and ambulance data were obtained from surveillance and administrative databases, while mortality data were obtained from the state death registry. The observed counts were compared with the average counts from the same period from 2006/07 through 2009/10, and a Poisson regression model was constructed to calculate the number of excess ED visits, ambulance and deaths after adjusting for calendar and lag effects.
  
  
  RESULTS
  During the heat wave there were 104 and 236 ED visits for heat effects and dehydration respectively, and 116 ambulance calls for heat exposure. From the regression model, all-cause ED visits increased by 2% (95% CI 1.01-1.03), all-cause ambulance calls increased by 14% (95% CI 1.11-1.16), and all-cause mortality increased by 13% (95% CI 1.06-1.22). Those aged 75 years and older had the highest excess rates of all outcomes.
  
  
  CONCLUSIONS
  The 2011 heat wave resulted in an increase in the number of ED visits and ambulance calls, especially in older persons, as well as an increase in all-cause mortality. Rapid surveillance systems provide markers of heat wave impacts that have fatal outcomes.
authors.affiliation: Centre for Epidemiology and Research, New South Wales Department of Health, Sydney, Australia. andrea.schaffer@sydney.edu.au
authors.forename: Andrea
authors.initials: A
authors.lastname: Schaffer
authors.forename: David
authors.initials: D
authors.lastname: Muscatello
authors.forename: Richard
authors.initials: R
authors.lastname: Broome
authors.forename: Stephen
authors.initials: S
authors.lastname: Corbett
authors.forename: Wayne
authors.initials: W
authors.lastname: Smith
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000552:Ambulances / Q000706:statistics & numerical data*; D003681:Dehydration / Q000453:epidemiology / Q000401:mortality* / Q000628:therapy; D004190:Disasters; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D018883:Heat Stroke / Q000453:epidemiology / Q000401:mortality* / Q000628:therapy; D006358:Hot Temperature; D006801:Humans; D008875:Middle Aged; D009026:Mortality; D009517:New South Wales / Q000453:epidemiology; D055815:Young Adult