title: The epidemiology of Hajj-related critical illness: lessons for deployment of temporary critical care services*.
abstract: BACKGROUND
  The annual Hajj experience has direct relevance for other jurisdictions planning rapid deployment strategies for intensive care for large groups during expected or emergent events.
  
  
  OBJECTIVE
  Approximately 2-3 million Muslims from over 160 countries travel to Saudi Arabia each year for Hajj. These pilgrims are typically older adults with a spectrum of comorbid conditions and of various ethnicities. This, coupled with a 2-wk period of physical migration in close contact with others, can lead to acute and critical illness from a variety of infectious and noninfectious causes and a requirement for full-scale but temporary intensive care to a large population. We describe patient characteristics, patterns of disease, and critical illness, including episodes of Influenza A 2009 (H1N1), therapies delivered, and clinical outcomes.
  
  
  METHODS
  Prospective cohort study of 110 critically ill patients in four hospitals during the 2009 ("1431": November 18 to December 4) Hajj in Saudi Arabia.
  
  
  RESULTS
  Median (interquartile range) age was 60.5 (51.3-70) yrs, 69 (62.7%) were male, and Acute Physiology and Chronic Health Evaluation IV score was 60.5 (47-78.3). Forty-one patients (37.3%) were critically ill due to cardiovascular diseases (23.6% with myocardial infarction); 51 (46.4%) had severe infections (21.8% with H1N1); electrolyte disturbance (21.8%); or pulmonary illness (15.5%). Sixty patients (54.6%) required ventilation. Median predicted mortality by Acute Physiology and Chronic Health Evaluation IV was 14% while actual short-term mortality was 6.4% (p = .009). Longer-term mortality may be higher.
  
  
  CONCLUSIONS
  Both event-specific conditions and patient-specific comorbid conditions are common causes of critical illness during large gatherings. With the ability to provide temporary but full-service intensive care, morbidity and mortality due to critical illness can be low, even among an older patient population and difficult care conditions.
authors.affiliation: Department of Intensive Care Services, Riyadh Military Hospital, Riyadh, Kingdom of Saudi Arabia. mandourah@hotmail.com
authors.forename: Yasser
authors.initials: Y
authors.lastname: Mandourah
authors.forename: Ali
authors.initials: A
authors.lastname: Ocheltree
authors.forename: Assim
authors.initials: A
authors.lastname: Al Radi
authors.forename: Robert
authors.initials: R
authors.lastname: Fowler
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003422:Critical Care / Q000458:organization & administration*; D016638:Critical Illness / Q000453:epidemiology*; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human; D007514:Islam; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012529:Saudi Arabia; D013997:Time Factors; D014195:Travel; D055815:Young Adult