title: The efficacy of the cystatin C based glomerular filtration rate in the estimation of safe contrast media volume.
abstract: OBJECTIVE
  The risk of contrast-induced nephropathy (CIN) is significantly influenced by baseline renal function and the amount of contrast media (CM). We evaluated the usefulness of the cystatin C (CyC) based estimated glomerular filtration rate (eGFRCyC) in the prediction of CIN and to determine the safe CM dosage.
  
  
  METHODS
  We prospectively enrolled a total of 723 patients who received percutaneous coronary intervention (PCI) and investigated the clinical factors associated with the development of CIN. Renal function was calculated as eGFRCyC and a modified diet in the renal disease (MDRD) equation, respectively. Systemic exposure of CM was calculated as CM volume to eGFR ratio. We conducted a regression analysis to evaluate the predictive role of CM volume to eGFRCyC for the risk of CIN.
  
  
  RESULTS
  The incidence of CIN was 4.0% (29/723). The patients with CIN had a lower hemoglobin level, decreased renal function, and a higher CyC value, and had greater CM exposure. Through multivariate regression analyses, hemoglobin {odds ratio (OR) 0.743, p=0.032}, CM volume/eGFRCyC (OR 1.697, p=0.006) and CM volume/MDRD (OR 2.275, p<0.001) were found to be independent predictors for CIN. In the receiver operating characteristic curve analysis, fair discrimination for CIN was found at a CM volume/eGFRCyC level of 4.493 (C-statics=0.814), and at this value, the sensitivity and specificity were 79.3% and 80.0%, respectively.
  
  
  CONCLUSIONS
  Both the CM volume/MDRD and CM volume/eGFRCyC method would be simple, useful indicators for determining the safe CM-dose based on eGFR value before PCI. However, there was no significantly different predictive value between creatinine and CyC based GFR estimations.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Keimyung University Dongsan Medical Center, Daegu, Korea.
authors.forename: Hyuck-Jun
authors.initials: HJ
authors.lastname: Yoon
authors.forename: Hyungseop
authors.initials: H
authors.lastname: Kim
authors.forename: Jae-Pil
authors.initials: JP
authors.lastname: Lee
authors.forename: Sang-Woong
authors.initials: SW
authors.lastname: Choi
authors.forename: Hyun-Ok
authors.initials: HO
authors.lastname: Cho
authors.forename: Hong-Won
authors.initials: HW
authors.lastname: Shin
authors.forename: Hyoung-Seob
authors.initials: HS
authors.lastname: Park
authors.forename: Yun-Kyeong
authors.initials: YK
authors.lastname: Cho
authors.forename: Chang-Wook
authors.initials: CW
authors.lastname: Nam
authors.forename: Seung-Ho
authors.initials: SH
authors.lastname: Hur
authors.forename: Yoon-Nyun
authors.initials: YN
authors.lastname: Kim
authors.forename: Kwon-Bae
authors.initials: KB
authors.lastname: Kim
keywords: Acute kidney injury; Contrast media; Cystatin C; Glomerular filtration rate