title: Association of heat index and patient volume at a mass gathering event.
abstract: In 1999, a department of emergency medicine was asked to provide medical care at a football stadium with a capacity of 61,625. Over four seasons, the department's experience has been that the number of patients seen during a game correlates closely with game-time heat and humidity (heat index).
  
  
  OBJECTIVE
  To determine how closely the heat index is associated with the number of patients who will require care at a mass gathering event.
  
  
  METHODS
  This was a retrospective review of all patient care from 1999 to 2003 at a Division I college football stadium located in the southeastern United States. All patrons seen in two emergency care centers (ECCs) were included. To control for stadium attendance, the Pearson product-moment correlation (PPMC) was calculated for each game. This statistical tool determines whether there is a positive correlation between heat index and ratio of number of patients cared for per 10,000 patrons.
  
  
  RESULTS
  A total of 20 games occurred, and the heat index ranged from 33 to 92. Number of patients varied from 15 to 74, and stadium attendance ranged from 53,371 to 61,625. The PPMC was calculated as 0.607, which indicates a strong positive correlation between heat index and patient volume (p < 0.005). Linear modeling predicts that for every 10-degree increase in the heat index, three more patients per 10,000 patrons will require care.
  
  
  CONCLUSIONS
  In this retrospective study, the heat index was strongly associated with the volume of patients who would be seen at a mass gathering event.
authors.affiliation: Department of Emergency Medicine, Maine Medical Center, Portland, Maine 04102, USA. perroa@mmc.org
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Perron
authors.forename: William J
authors.initials: WJ
authors.lastname: Brady
authors.forename: Catherine B
authors.initials: CB
authors.lastname: Custalow
authors.forename: David M
authors.initials: DM
authors.lastname: Johnson
mesh_terms: D003441:Crowding / Q000503:physiopathology*; D004632:Emergency Medical Services / Q000706:statistics & numerical data*; D005260:Female; D005392:First Aid / Q000706:statistics & numerical data; D005538:Football; D006359:Heat Exhaustion / Q000453:epidemiology*; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D008297:Male; D008399:Mass Behavior; D011336:Probability; D012189:Retrospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D013997:Time Factors