title: A comparison of nonoliguric and oliguric severe acute kidney injury according to the risk injury failure loss end-stage (RIFLE) criteria.
abstract: BACKGROUND
  Risk, Injury, Failure, Loss, and End-Stage (RIFLE) criteria have been proposed as a standard definition of acute kidney injury (AKI). The most severe form of AKI, class F AKI, can be defined by either severe oliguria or a 3-fold increase in serum creatinine concentrations. We hypothesized that the outcomes of patients with these 2 alternative criteria of severe AKI were different.
  
  
  METHODS
  A prospective cohort study was conducted of all patients attaining RIFLE class F AKI during a 12-month period in a tertiary critical care facility.
  
  
  RESULTS
  Among a total of 2,379 critical care admissions, 129 (5.4%) fulfilled the serum creatinine criteria without oliguria (RIFLE class F) and 99 (4.2%) fulfilled oliguric (RIFLE class F) AKI criteria. Patients with oliguric AKI suffered a more severe disease process than nonoliguric AKI. Oliguric AKI was associated with a significantly higher risk of requiring acute dialysis (70.7 vs. 22.4%, p = 0.001), long-term dialysis >90 days (15 vs. 1.9%, p = 0.006), and hospital mortality (adjusted hazard ratio 3.33, 95% confidence interval, p = 0.001) than nonoliguric AKI.
  
  
  CONCLUSIONS
  Oliguric RIFLE class F AKI is a more severe form of AKI than nonoliguric class F AKI. These 2 forms of AKI should be considered separately when AKI is evaluated in a clinical trial.
authors.affiliation: Department of Intensive Care Medicine, Royal Perth Hospital, Perth, W.A., Australia. davidintoronto2004@hotmail.com
authors.forename: David J R
authors.initials: DJ
authors.lastname: Morgan
authors.forename: Kwok M
authors.initials: KM
authors.lastname: Ho
mesh_terms: D058186:Acute Kidney Injury / Q000175:diagnosis* / Q000401:mortality*; D001315:Australia / Q000453:epidemiology; D015897:Comorbidity; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D015994:Incidence; D007676:Kidney Failure, Chronic / Q000175:diagnosis* / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D009846:Oliguria / Q000175:diagnosis* / Q000401:mortality*; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D015996:Survival Rate