title: Predictive performance of glomerular filtration rate estimation equations based on cystatin C versus serum creatinine values in critically ill patients.
abstract: OBJECTIVE
  The predictive performance of glomerular filtration rate (GFR) estimation equations based on cystatin C versus serum creatinine (SCr) values in critically ill patients was evaluated.
  
  
  METHODS
  A retrospective observational study was performed in the medical intensive care unit (ICU) of a university hospital from October 2006 through September 2007. All consecutively admitted critically ill patients older than 18 years who stayed in the ICU for more than 48 hours with a urinary bladder catheter in place were included in the study. Data collected included SCr, cystatin C, serum albumin, blood urea nitrogen, and 24-hour urine creatinine clearance [Formula: see text] levels. The following equations were also used to determine the estimated GFR that was compared with the reference [Formula: see text] for all patients in the study: Arnal-Dade using cystatin C, Cockcroft-Gault using actual body weight, Cockcroft-Gault using ideal body weight, Jelliffe, Modification of Diet in Renal Disease (MDRD), and four-variable version MDRD (MDRD-4).
  
  
  RESULTS
  This study included 241 measurements corresponding to 131 critically ill patients. The cystatin C-based equation underestimated [Formula: see text], whereas overestimation by every SCr-based formula was observed in the whole cohort and in the [Formula: see text] subgroup; MDRD-4 was the most biased equation in every analysis. There were no significant differences in precision, except for great variability in the subgroup with a [Formula: see text] of <60 mL/min/1.73 m(2), where the MDRD equation showed better results than the cystatin C-based equation (33.5% versus 38.9%). No equations fulfilled concordance requirements with [Formula: see text].
  
  
  CONCLUSIONS
  A retrospective observational study showed no evidence of superiority of a cystatin C-based equation over SCr-based equations to estimate the GFR in an ICU population.
authors: Pharmacy Department, Hospital Clinic of Barcelona, Institut D'Investigacions Biomediques August Pi I Sunyer, University of Barcelona, Barcelona, Spain.
authors: Elisa
authors: E
authors: Diego
authors: Medical Intensive Care Unit, Hospital Clinic of Barcelona, Institut D'Investigacions Biomediques August Pi I Sunyer, University of Barcelona, Barcelona, Spain. pcastro@clinic.ub.es.
authors: Pedro
authors: P
authors: Castro
authors: Pharmacy Department, Hospital Clinic of Barcelona, Institut D'Investigacions Biomediques August Pi I Sunyer, University of Barcelona, Barcelona, Spain.
authors: Dolors
authors: D
authors: Soy
authors: Nephrology and Transplantation Department, Hospital Clinic of Barcelona, Institut D'Investigacions Biomediques August Pi I Sunyer, University of Barcelona, Barcelona, Spain.
authors: Esteban
authors: E
authors: Poch
authors: Medical Intensive Care Unit, Hospital Clinic of Barcelona, Institut D'Investigacions Biomediques August Pi I Sunyer, University of Barcelona, Barcelona, Spain.
authors: Josep M
authors: JM
authors: Nicolás
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003404:Creatinine / Q000097:blood* / Q000652:urine; D016638:Critical Illness; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007362:Intensive Care Units; D007674:Kidney Diseases / Q000175:diagnosis*; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D055316:Cystatin C; D003404:Creatinine