title: Transient versus persistent acute kidney injury and the diagnostic performance of fractional excretion of urea in critically ill patients.
abstract: OBJECTIVE
  To evaluate the performance of fractional excretion of urea (FeU) for differentiating transient (T) from persistent (P) acute kidney injury (AKI) and to assess performance of FeU in predicting AKI in patients admitted to the ICU.
  
  
  METHODS
  We performed secondary analysis of a multicenter prospective observational cohort study on the predictive performance of biological markers for AKI in critically ill patients. AKI was diagnosed according to RIFLE staging.
  
  
  RESULTS
  Of 150 patients, 51 and 41 patients were classified as having T-AKI and P-AKI, respectively. The diagnostic performance for FeU to discriminate T-AKI from P-AKI on the day of AKI was poor (AUC-ROC = 0.61; 95% CI: 0.49-0.73). The diagnostic performance of FeU to predict AKI 1 and 2 days prior to AKI was poor as well (AUC-ROC = 0.61; 95% CI: 0.47-0.74, and 0.58; 95% CI: 0.43-0.73, respectively).
  
  
  CONCLUSIONS
  FeU does not seem to be helpful in differentiating T- from P-AKI in critically ill patients and it is a poor predictor of AKI.
authors.affiliation: Department of Medical Informatics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: K A
authors.initials: KA
authors.lastname: Wlodzimirow
authors.forename: A
authors.initials: A
authors.lastname: Abu-Hanna
authors.forename: A A N M
authors.initials: AA
authors.lastname: Royakkers
authors.forename: P E
authors.initials: PE
authors.lastname: Spronk
authors.forename: L S
authors.initials: LS
authors.lastname: Hofstra
authors.forename: M A
authors.initials: MA
authors.lastname: Kuiper
authors.forename: M J
authors.initials: MJ
authors.lastname: Schultz
authors.forename: C S C
authors.initials: CS
authors.lastname: Bouman
mesh_terms: D058186:Acute Kidney Injury / Q000145:classification* / Q000175:diagnosis* / Q000652:urine; D000328:Adult; D000368:Aged; D019540:Area Under Curve; D015415:Biomarkers / Q000652:urine; D003422:Critical Care; D016638:Critical Illness; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D014508:Urea / Q000652:urine*
chemical_list: D015415:Biomarkers; D014508:Urea