title: Acute kidney injury among critically ill patients with pandemic H1N1 influenza A in Canada: cohort study.
abstract: BACKGROUND
  Canada's pandemic H1N1 influenza A (pH1N1) outbreak led to a high burden of critical illness. Our objective was to describe the incidence of AKI (acute kidney injury) in these patients and risk factors for AKI, renal replacement therapy (RRT), and mortality.
  
  
  METHODS
  From a prospective cohort of critically ill adults with confirmed or probable pH1N1 (16 April 2009-12 April 2010), we abstracted data on demographics, co-morbidities, acute physiology, AKI (defined by RIFLE criteria for Injury or Failure), treatments in the intensive care unit, and clinical outcomes. Univariable and multivariable logistic regression analyses were used to evaluate the associations between clinical characteristics and the outcomes of AKI, RRT, and hospital mortality.
  
  
  RESULTS
  We included 562 patients with pH1N1-related critical illness (479 [85.2%] confirmed, 83 [14.8%] probable]: mean age 48.0 years, 53.4% female, and 13.3% aboriginal. Common co-morbidities included obesity, diabetes, and chronic obstructive pulmonary disease. AKI occurred in 60.9%, with RIFLE categories of Injury (23.0%) and Failure (37.9%). Independent predictors of AKI included obesity (OR 2.94; 95%CI, 1.75-4.91), chronic kidney disease (OR 4.50; 95%CI, 1.46-13.82), APACHE II score (OR per 1-unit increase 1.06; 95%CI, 1.03-1.09), and P(a)O2/F(i)O2 ratio (OR per 10-unit increase 0.98; 95%CI, 0.95-1.00). Of patients with AKI, 24.9% (85/342) received RRT and 25.8% (85/329) died. Independent predictors of RRT were obesity (OR 2.25; 95% CI, 1.14-4.44), day 1 mechanical ventilation (OR 4.09; 95% CI, 1.21-13.84), APACHE II score (OR per 1-unit increase 1.07; 95% CI, 1.03-1.12), and day 1 creatinine (OR per 10 μmol/L increase, 1.06; 95%CI, 1.03-1.10). Development of AKI was not independently associated with hospital mortality.
  
  
  CONCLUSIONS
  The incidence of AKI and RRT utilization were high among Canadian patients with critical illness due to pH1N1.
authors.affiliation: Division of Critical Care Medicine, Faculty of Medicine and Dentistry, University of Alberta, 3C1.12 Walter C Mackenzie Centre, 8440-112 St NW, Edmonton, AB T6G 2B7, Canada.
authors.forename: Sean M
authors.initials: SM
authors.lastname: Bagshaw
authors.forename: Manish M
authors.initials: MM
authors.lastname: Sood
authors.forename: Jennifer
authors.initials: J
authors.lastname: Long
authors.forename: Robert A
authors.initials: RA
authors.lastname: Fowler
authors.forename: Neill K J
authors.initials: NK
authors.lastname: Adhikari
mesh_terms: D058186:Acute Kidney Injury / Q000175:diagnosis / Q000453:epidemiology*; D000328:Adult; D002170:Canada / Q000453:epidemiology; D015331:Cohort Studies; D016638:Critical Illness / Q000453:epidemiology*; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D058873:Pandemics; D011446:Prospective Studies