title: Which method of estimating renal function is the best predictor of mortality after coronary artery bypass grafting?
abstract: OBJECTIVE
  Definitions of renal function in patients undergoing coronary artery bypass graft surgery (CABG) vary in the literature. We sought to investigate which method of estimating renal function is the best predictor of mortality after CABG.
  
  
  METHODS
  We analysed the preoperative and postoperative renal function data from all patients undergoing isolated CABG from January 1998 through December 2007. Preoperative and postoperative renal function was estimated using serum creatinine (SeCr) levels, creatinine clearance (CrCl) determined by the Cockcroft-Gault formula and the glomerular filtration rate (e-GFR) estimated by the Modification of Diet in Renal Disease (MDRD) formula. Receiver operator characteristic (ROC) curves and area under the ROC curves were calculated.
  
  
  RESULTS
  In 9987 patients, CrCl had the best discriminatory power to predict early as well as late mortality, followed by e-GFR and finally SeCr. The odds ratios for preoperative parameters for early mortality were closer to 1 than those of the postoperative parameters.
  
  
  CONCLUSIONS
  Renal function determined by the Cockcroft-Gault formula is the best predictor of early and late mortality after CABG. The relationship between renal function and mortality is non-linear. Renal function as a variable in risk scoring systems such as the EuroSCORE needs to be reconsidered.
authors.affiliation: Department of Cardiothoracic Surgery, Catharina Hospital, Michelangelolaan 2, PO Box 1350, 5602 ZA, Eindhoven, the Netherlands.
authors.forename: A H M
authors.initials: AH
authors.lastname: van Straten
authors.forename: M A
authors.initials: MA
authors.lastname: Soliman Hamad
authors.forename: B M J A
authors.initials: BM
authors.lastname: Koene
authors.forename: E J
authors.initials: EJ
authors.lastname: Martens
authors.forename: M E S H
authors.initials: ME
authors.lastname: Tan
authors.forename: E
authors.initials: E
authors.lastname: Berreklouw
authors.forename: A A J
authors.initials: AA
authors.lastname: van Zundert