title: Changing incidence and outcomes following dialysis-requiring acute kidney injury among critically ill adults: a population-based cohort study.
abstract: BACKGROUND
  Dialysis-requiring acute kidney injury (AKI) is common among critically ill patients, but little is known about trends in the incidence and outcomes of this condition over time.
  
  
  METHODS
  Population-based cohort study.
  
  
  METHODS
  All adult patients admitted to an intensive care unit in Ontario, Canada, 1996 to 2010.
  
  
  METHODS
  Year and era (1996-2000, 2001-2005, and 2006-2010) of cohort entry.
  
  
  RESULTS
  Mortality and dialysis dependence, each evaluated at 90 and 365 days after initiation of dialysis therapy for AKI.
  
  
  METHODS
  The annual incidence proportion of dialysis-requiring AKI was evaluated and patients with this condition were characterized by era. Associations between era and the outcomes of interest were evaluated with Cox proportional hazards (for time to death) and logistic regression (for dialysis dependence), with adjustment for relevant demographic and clinical variables.
  
  
  RESULTS
  The annual incidence of dialysis-requiring AKI among critically ill patients increased from 0.8% in 1996 to 3.0% in 2010 (P for trend < 0.001). 90-day mortality declined from 50% in 1996 to 2000 to 45% in 2006 to 2010 (adjusted HR, 0.83 [95% CI, 0.79-0.87] compared to 1996-2000). Dialysis dependence among surviving patients at 90 days was marginally lower in 2006 to 2010 (25.1%) compared to 1996 to 2000 (27.2%), but after adjustment for confounding factors, was not significantly different (adjusted OR, 0.91; 95% CI, 0.80-1.03).
  
  
  CONCLUSIONS
  Unmeasured confounding by factors that may have changed in patients with dialysis-requiring AKI during the different eras; data set does not allow for mechanistic explanation for the findings; and lack of access to laboratory investigations after hospital discharge.
  
  
  CONCLUSIONS
  The incidence proportion of dialysis-requiring AKI among critically ill patients increased by almost 4-fold between 1996 and 2010. This was accompanied by a significant decline in mortality, but the risk of long-term dialysis dependence continues to affect a substantial minority of surviving patients with no clear evidence of improvement over time.
authors.affiliation: Division of Nephrology, St Michael's Hospital and University of Toronto, Toronto, ON, Canada; Li Ka Shing Knowledge Institute of St Michael's Hospital, Toronto, ON, Canada; Institute for Clinical Evaluative Sciences Kidney, Dialysis and Transplantation Program, London, ON, Canada. Electronic address: waldr@smh.ca.
authors.forename: Ron
authors.initials: R
authors.lastname: Wald
authors.affiliation: Institute for Clinical Evaluative Sciences Kidney, Dialysis and Transplantation Program, London, ON, Canada.
authors.forename: Eric
authors.initials: E
authors.lastname: McArthur
authors.affiliation: Interdepartmental Division of Critical Care, University of Toronto, Toronto, ON, Canada; Department of Critical Care Medicine and Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.
authors.forename: Neill K J
authors.initials: NK
authors.lastname: Adhikari
authors.affiliation: Division of Critical Care Medicine, University of Alberta Hospital, Edmonton, AB, Canada.
authors.forename: Sean M
authors.initials: SM
authors.lastname: Bagshaw
authors.affiliation: Li Ka Shing Knowledge Institute of St Michael's Hospital, Toronto, ON, Canada; Interdepartmental Division of Critical Care, University of Toronto, Toronto, ON, Canada; Department of Critical Care, St Michael's Hospital, Toronto, ON, Canada; Department of Medicine, St Michael's Hospital, Toronto, ON, Canada.
authors.forename: Karen E A
authors.initials: KE
authors.lastname: Burns
authors.affiliation: Division of Nephrology, Department of Medicine, University of Western Ontario, London, ON, Canada.
authors.forename: Amit X
authors.initials: AX
authors.lastname: Garg
authors.affiliation: Division of Nephrology, St Michael's Hospital and University of Toronto, Toronto, ON, Canada; Li Ka Shing Knowledge Institute of St Michael's Hospital, Toronto, ON, Canada; Institute for Clinical Evaluative Sciences Kidney, Dialysis and Transplantation Program, London, ON, Canada.
authors.forename: Ziv
authors.initials: Z
authors.lastname: Harel
authors.affiliation: Division of Nephrology, St Michael's Hospital and University of Toronto, Toronto, ON, Canada.
authors.forename: Abhijat
authors.initials: A
authors.lastname: Kitchlu
authors.affiliation: Li Ka Shing Knowledge Institute of St Michael's Hospital, Toronto, ON, Canada; Department of Anesthesia, St Michael's Hospital and University of Toronto, Toronto, ON, Canada.
authors.forename: C David
authors.initials: CD
authors.lastname: Mazer
authors.affiliation: Institute for Clinical Evaluative Sciences Kidney, Dialysis and Transplantation Program, London, ON, Canada.
authors.forename: Danielle M
authors.initials: DM
authors.lastname: Nash
authors.affiliation: Interdepartmental Division of Critical Care, University of Toronto, Toronto, ON, Canada; Department of Critical Care Medicine and Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.
authors.forename: Damon C
authors.initials: DC
authors.lastname: Scales
authors.affiliation: Division of Nephrology, St Michael's Hospital and University of Toronto, Toronto, ON, Canada.
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Silver
authors.affiliation: Li Ka Shing Knowledge Institute of St Michael's Hospital, Toronto, ON, Canada; Division of General Internal Medicine, St Michael's Hospital and University of Toronto, Toronto, ON, Canada.
authors.forename: Joel G
authors.initials: JG
authors.lastname: Ray
authors.affiliation: Li Ka Shing Knowledge Institute of St Michael's Hospital, Toronto, ON, Canada; Interdepartmental Division of Critical Care, University of Toronto, Toronto, ON, Canada; Department of Critical Care, St Michael's Hospital, Toronto, ON, Canada; Department of Medicine, St Michael's Hospital, Toronto, ON, Canada.
authors.forename: Jan O
authors.initials: JO
authors.lastname: Friedrich
mesh_terms: D058186:Acute Kidney Injury / Q000453:epidemiology* / Q000401:mortality / Q000628:therapy; D000368:Aged; D015331:Cohort Studies; D016638:Critical Illness / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007362:Intensive Care Units; D007676:Kidney Failure, Chronic / Q000453:epidemiology* / Q000628:therapy; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D016016:Proportional Hazards Models; D006435:Renal Dialysis; D051436:Renal Insufficiency, Chronic / Q000453:epidemiology; D012720:Severity of Illness Index; D016896:Treatment Outcome
keywords: AKI incidence; Acute kidney injury (AKI); clinical outcomes; critical care unit; dialysis; dialysis dependence; end-stage renal disease (ESRD); intensive care unit (ICU); mortality; renal replacement therapy (RRT); secular trend