title: Presurgical serum cystatin C and risk of acute kidney injury after cardiac surgery.
abstract: BACKGROUND
  Acute kidney injury (AKI) after cardiac surgery is associated with poor outcomes, but is challenging to predict from information available before surgery.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  The TRIBE-AKI (Translational Research Investigating Biomarker Endpoints in Acute Kidney Injury) Consortium enrolled 1,147 adults undergoing cardiac surgery at 6 hospitals from 2007-2009; participants were selected for high AKI risk.
  
  
  METHODS
  Presurgical values for cystatin C, creatinine, and creatinine-based estimated glomerular filtration rate (eGFR) were categorized into quintiles and grouped as "best" (quintiles 1-2), "intermediate" (quintiles 3-4), and "worst" (quintile 5) kidney function.
  
  
  RESULTS
  The primary outcome was AKI Network (AKIN) stage 1 or higher; ≥0.3 mg/dL or 50% increase in creatinine level.
  
  
  METHODS
  Analyses were adjusted for characteristics used clinically for presurgical risk stratification.
  
  
  RESULTS
  Average age was 71 ± 10 years (mean ± standard deviation); serum creatinine, 1.1 ± 0.3 mg/dL; eGFR-Cr, 74 ± 9 mL/min/1.73 m(2); and cystatin C, 0.9 ± 0.3 mg/L. 407 (36%) participants developed AKI during hospitalization. Adjusted odds ratios for intermediate and worst kidney function by cystatin C were 1.9 (95% CI, 1.4-2.7) and 4.8 (95% CI, 2.9-7.7) compared with 1.2 (95% CI, 0.9-1.7) and 1.8 (95% CI, 1.2-2.6) for creatinine and 1.0 (95% CI, 0.7-1.4) and 1.7 (95% CI, 1.1-2.3) for eGFR-Cr categories, respectively. After adjustment for clinical predictors, the C statistic to predict AKI was 0.70 without kidney markers, 0.69 with creatinine, and 0.72 with cystatin C. Cystatin C also substantially improved AKI risk classification compared with creatinine, based on a net reclassification index of 0.21 (P < 0.001).
  
  
  CONCLUSIONS
  The ability of these kidney biomarkers to predict risk of dialysis-requiring AKI or death could not be assessed reliably in our study because of a small number of patients with either outcome.
  
  
  CONCLUSIONS
  Presurgical cystatin C is better than creatinine or creatinine-based eGFR at forecasting the risk of AKI after cardiac surgery.
authors: Department of Medicine, San Francisco VA Medical Center and University of California, San Francisco, San Francisco, CA, USA.
authors: Michael G
authors: MG
authors: Shlipak
authors: Steven G
authors: SG
authors: Coca
authors: Zhu
authors: Z
authors: Wang
authors: Prasad
authors: P
authors: Devarajan
authors: Jay L
authors: JL
authors: Koyner
authors: Uptal D
authors: UD
authors: Patel
authors: Heather
authors: H
authors: Thiessen-Philbrook
authors: Amit X
authors: AX
authors: Garg
authors: Chirag R
authors: CR
authors: Parikh
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