title: Predictive power of serum cystatin C to detect acute kidney injury and pediatric-modified RIFLE class in children undergoing cardiac surgery.
abstract: OBJECTIVE
  Acute kidney injury is a frequent and serious complication of cardiopulmonary bypass. In current clinical practice, serum creatinine is used to detect acute kidney injury. Cystatin C is a novel biomarker for kidney function that has been shown to be superior to serum creatinine in predicting acute kidney injury in adults after cardiopulmonary bypass. The aim of this study was to determine whether early cystatin C levels predict acute kidney injury associated with cardiopulmonary bypass in pediatric patients undergoing cardiac surgery and if cystatin C could predict pediatric-modified RIFLE (Risk, Injury, Failure, Loss, End-stage kidney disease) class and renal injury as determined by estimated glomerular filtration rate. We also investigated whether ultrafiltration during cardiopulmonary bypass affects cystatin C levels.
  
  
  METHODS
  Prospective, observational cohort study.
  
  
  METHODS
  Cardiac intensive care unit in a tertiary, academic pediatric hospital.
  
  
  METHODS
  One hundred pediatric patients who underwent cardiac surgery involving cardiopulmonary bypass.
  
  
  METHODS
  None.
  
  
  RESULTS
  Acute kidney injury was defined as a 50% increase in serum creatinine from a preoperative baseline anytime through postoperative day 4. Severity of acute kidney injury was determined by pediatric RIFLE class using estimated glomerular filtration rate criteria only. Renal injury was also determined by an absolute estimated glomerular filtration rate <80 mL/min/1.73 m. Cystatin C levels were measured before and after ultrafiltration. Twenty-eight patients (28%) developed acute kidney injury. Cystatin C predicted acute kidney injury as early as 8 hrs after surgery. When applying pediatric RIFLE criteria to the entire study, 30 patients reached "risk" and five developed "injury." Cystatin C was a good predictor of the development of "injury" (under the receiver operating characteristic curve, 0.834-0.875) and of renal injury by estimated glomerular filtration rate (under the receiver operating characteristic curve, 0.717-0.835) (all p < .05). Cystatin C levels decreased perioperatively and correlated with volume of fluid removed by ultrafiltration.
  
  
  CONCLUSIONS
  Cystatin C is an early predictor of acute kidney injury in children after cardiopulmonary bypass. Cystatin C is a good predictor of pediatric RIFLE classification and of decreased estimated glomerular filtration rate after cardiopulmonary bypass. Serum cystatin C may be cleared by ultrafiltration.
authors.affiliation: Division of Pediatric Critical Care, Children's Memorial Hospital, Chicago, IL, USA.
authors.forename: Amanda B
authors.initials: AB
authors.lastname: Hassinger
authors.forename: Carl L
authors.initials: CL
authors.lastname: Backer
authors.forename: Jerome C
authors.initials: JC
authors.lastname: Lane
authors.forename: Shannon
authors.initials: S
authors.lastname: Haymond
authors.forename: Deli
authors.initials: D
authors.lastname: Wang
authors.forename: Eric L
authors.initials: EL
authors.lastname: Wald
mesh_terms: D058186:Acute Kidney Injury / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D003404:Creatinine / Q000097:blood; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006330:Heart Defects, Congenital / Q000601:surgery*; D006801:Humans; D007223:Infant; D008297:Male; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D019616:Thoracic Surgical Procedures
chemical_list: D015415:Biomarkers; D055316:Cystatin C; D003404:Creatinine