title: Discrepancies in the RIFLE classification are due to the method used to assess the level of derangement of kidney function.
abstract: OBJECTIVE
  We hypothesized that RIFLE based on creatinine clearance (CrCl) is superior to that based on serum creatinine (sCr) or Cockroft-Gault (C-G) because it is an earlier marker of kidney dysfunction.
  
  
  METHODS
  At day 3 of admission, we compared the RIFLE based on sCr, C-G, and CrCl with 28-day mortality and development of RIFLE-F during intensive care unit stay.
  
  
  RESULTS
  Percentages in the RIFLE levels were similar for the 3 estimates, but the patients included in each level were different; with CrCl as the reference, κ statistic was 0.29 (95% confidence interval, 0.15-0.43) for sCr and 0.21 (0.07-0.36) for C-G. Mortality at day 28 was 19.3%, with percentages of mortality increasing with RIFLE based in CrCl but not sCr or C-G (area under the curve, 0.57 [45-72] for C-G; 0.57 [44-72] for sCr; and 0.64 [52-79] for CrCl). Logistic regression only showed an independent relationship with mortality for RIFLE measured with CrCl.
  
  
  CONCLUSIONS
  RIFLE classification using sCr or C-G at the third day of admission predicts outcome less accurately than with the use of CrCl. Because of the delay in the rise of sCr after a sudden glomerular filtration rate decrease, RIFLE based in CrCl may represent an advantage in terms of precocity.
authors: Critical Care and Emergency Unit, University Hospital Carlos Haya, Malaga, 29010, Spain. mehguci@gmail.com
authors: Manuel E
authors: ME
authors: Herrera-Gutiérrez
authors: Gemma
authors: G
authors: Seller-Pérez
authors: Esther
authors: E
authors: Banderas-Bravo
authors: Cesar
authors: C
authors: Aragón-Gonzalez
authors: Rebeca
authors: R
authors: Olalla-Sánchez
authors: Rosario
authors: R
authors: Lozano-Sáez
mesh_terms: D058186:Acute Kidney Injury / Q000097:blood / Q000401:mortality* / Q000503:physiopathology*; D003404:Creatinine / Q000097:blood*; D003422:Critical Care; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D007677:Kidney Function Tests / Q000592:standards*; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012720:Severity of Illness Index; D013030:Spain; D016019:Survival Analysis
chemical_list: D003404:Creatinine