title: Influenza A (H1N1pdm09)-Related Critical Illness and Mortality in Mexico and Canada, 2014.
abstract: OBJECTIVE
  The 2009-2010 influenza A (H1N1pdm09) pandemic caused substantial morbidity and mortality among young patients; however, mortality estimates have been confounded by regional differences in eligibility criteria and inclusion of selected populations. In 2013-2014, H1N1pdm09 became North America's dominant seasonal influenza strain. Our objective was to compare the baseline characteristics, resources, and treatments with outcomes among critically ill patients with influenza A (H1N1pdm09) in Mexican and Canadian hospitals in 2014 using consistent eligibility criteria.
  
  
  METHODS
  Observational study and a survey of available healthcare setting resources.
  
  
  METHODS
  Twenty-one hospitals, 13 in Mexico and eight in Canada.
  
  
  METHODS
  Critically ill patients with confirmed H1N1pdm09 during 2013-2014 influenza season.
  
  
  METHODS
  None.
  
  
  RESULTS
  The main outcome measures were 90-day mortality and independent predictors of mortality. Among 165 adult patients with H1N1pdm09-related critical illness between September 2013 and March 2014, mean age was 48.3 years, 64% were males, and nearly all influenza was community acquired. Patients were severely hypoxic (median PaO2-to-FIO2 ratio, 83 mm Hg), 97% received mechanical ventilation, with mean positive end-expiratory pressure of 14 cm H2O at the onset of critical illness and 26.7% received rescue oxygenation therapy with prone ventilation, extracorporeal life support, high-frequency oscillatory ventilation, or inhaled nitric oxide. At 90 days, mortality was 34.6% (13.9% in Canada vs 50.5% in Mexico, p < 0.0001). Independent predictors of mortality included lower presenting PaO2-to-FIO2 ratio (odds ratio, 0.89 per 10-point increase [95% CI, 0.80-0.99]), age (odds ratio, 1.49 per 10 yr increment [95% CI, 1.10-2.02]), and requiring critical care in Mexico (odds ratio, 7.76 [95% CI, 2.02-27.35]). ICUs in Canada generally had more beds, ventilators, healthcare personnel, and rescue oxygenation therapies.
  
  
  CONCLUSIONS
  Influenza A (H1N1pdm09)-related critical illness still predominantly affects relatively young to middle-aged patients and is associated with severe hypoxemic respiratory failure. The local critical care system and available resources may be influential determinants of patient outcome.
authors.affiliation: 1Department of Critical Care Medicine, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico.2Escuela de Medicina, Tecnologico de Monterrey, Monterrey, Mexico.3Department of Hospital Epidemiology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico.4Trauma, Emergency and Critical Care, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada.5Department of Critical Care Medicine, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada.6Department of Critical Care Medicine, Instituto Nacional de Cancerología, Mexico City, Mexico.7Department of Infectious Diseases, Hospital universitario Dr. José Eleuterio González, Monterrey, Nuevo León, Mexico.8Department of Critical Care Medicine and Emergency, Instituto de Salud del Estado de México, Toluca, Mexico.9Department of Critical Care Medicine, Instituto Nacional de Enfermedades Respiratorias, Mexico City, Mexico.10Department of Critical Care Medicine, Hospital General de Tijuana, Tijuana, Baja California, Mexico.11Department of Critical Care Medicine, Hospital Central Ignacio Morones Prieto, San Luis Potosi, Mexico.12Department of Critical Care Medicine, Hospital General de Uruapan, Uruapan, Michoacan, Mexico.13Department of Infectious Diseases, Hospital General Regional de León, León, Guanajuato, Mexico.14Department of Infectious Diseases, Hospital Regional de Alta Especialidad de Oaxaca, Oaxaca, Mexico.15Department of Critical Care Medicine, Hospital General "Dr. Manuel Gea González," Mexico City, Mexico.16Department of Disasters Response, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico.17Department of Critical Care Medicine, Hospital San José Monterrey, Monterrey, Nuevo León, Mexico.18Faculty of Medicine, Universidad de Guanajuato, León, Guanajuato, Mexico.19Department of Critical Care Medicine, Hospital Regional de Alta Especialidad de Oaxaca, 
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mesh_terms: D000305:Adrenal Cortex Hormones / Q000191:economics / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D000998:Antiviral Agents / Q000191:economics / Q000627:therapeutic use; D002170:Canada / Q000453:epidemiology; D016638:Critical Illness / Q000453:epidemiology / Q000628:therapy*; D015199:Extracorporeal Membrane Oxygenation / Q000191:economics / Q000379:methods; D005260:Female; D005102:Health Expenditures; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000191:economics / Q000453:epidemiology / Q000503:physiopathology* / Q000628:therapy*; D007362:Intensive Care Units / Q000706:statistics & numerical data*; D008297:Male; D008800:Mexico / Q000453:epidemiology; D008875:Middle Aged; D012121:Respiration, Artificial / Q000191:economics / Q000379:methods; D012131:Respiratory Insufficiency / Q000503:physiopathology / Q000628:therapy
chemical_list: D000305:Adrenal Cortex Hormones; D000998:Antiviral Agents