title: Validating a scoring tool to predict acute kidney injury (AKI) following cardiac surgery.
abstract: BACKGROUND
  Acute kidney injury (AKI) after cardiac surgery is associated with an increased risk of mortality. Preoperative risk scores can identify patients at risk for AKI and facilitate preventive strategies. Currently, validated risk scores are used to predict AKI requiring dialysis (AKI-D); less is known about whether these tools predict less severe forms of AKI.
  
  
  OBJECTIVE
  To evaluate the Cleveland Clinic scoring tool in predicting both AKI-D and less severe stages of AKI in patients after cardiac surgery in a Canadian tertiary care center.
  
  
  METHODS
  Retrospective case-control study.
  
  
  METHODS
  Regina Qu'Appelle Health Region (RQHR) from 2007 to 2011.
  
  
  METHODS
  Patients who underwent cardiac surgery and developed postoperative kidney injury (n = 2316).
  
  
  METHODS
  Data on risk factors for AKI and outcomes of cardiac surgery were collected from a retrospective chart review.
  
  
  METHODS
  The primary outcome was AKI, defined as Stage 1 (increase in serum creatinine 1.5-1.9 X baseline within 5 days), Stage 2 (increase 2.0-2.9 X baseline), or Stage 3 (increase 3.0 X baseline or more OR initiation of dialysis during hospital stay). We assessed the performance of a modified version of the Cleveland Clinic tool using receiver operating curve analyses.
  
  
  RESULTS
  The incidence of AKI was 6.1% (Stage 1), 2.6% (Stage 2), and 5.8% (Stage 3). The area under the curve (AUC) for the Cleveland score was 0.61 (95% CI: 0.56 to 0.65; p < 0.001) for Stage 1, 0.61 (95% CI: 0.54 to 0.68; p < 0.01) for Stage 2, and 0.78 (95% CI: 0.74 to 0.82; p < 0.001) for Stage 3. Greater level of risk on the Cleveland tool was associated with a higher risk of Stage 3 AKI.
  
  
  CONCLUSIONS
  Lack of prospective validation.
  
  
  CONCLUSIONS
  The modified Cleveland Clinic tool was valid in identifying patients with severe stages of AKI but did not have strong discrimination for early AKI stages.
authors.affiliation: College of Medicine - Regina Campus, University of Saskatchewan, Regina General Hospital, 1440-14th Avenue, Regina, SK S4P0W5 Canada.
authors.forename: Brian
authors.initials: B
authors.lastname: Wong
authors.affiliation: Research and Performance Support, Regina Qu'Appelle Health Region, Regina, SK, 2180 - 23rd Avenue, Regina, SK S4S 0A5 Canada.
authors.forename: Jennifer
authors.initials: J
authors.lastname: St Onge
authors.affiliation: Department of Surgery, Regina Qu'Appelle Health Region, Regina, SK, Regina General Hospital, 1440-14th Avenue, Regina, SK S4P0W5 Canada.
authors.forename: Stephen
authors.initials: S
authors.lastname: Korkola
authors.affiliation: Section of Nephrology, Department of Medicine, Regina Qu'Appelle Health Region, Regina, SK, Regina General Hospital, 1440-14th Avenue, 3401-B Pasqua Street, Regina, SK S4P0W5 Canada.
authors.forename: Bhanu
authors.initials: B
authors.lastname: Prasad
keywords: Acute kidney injury; Cardiac surgery complication; Dialysis; Mortality; Serum creatinine