The Efficacy of the Cystatin C Based Glomerular Filtration Rate in the Estimation of Safe Contrast Media Volume

BACKGROUND AND OBJECTIVES: 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 (eGFR(CyC)) in the prediction of CIN and to determine the safe CM dosage. SUBJECTS AND 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 eGFR(CyC) 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 eGFR(CyC) 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/eGFR(CyC) (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/eGFR(CyC) level of 4.493 (C-statics=0.814), and at this value, the sensitivity and specificity were 79.3% and 80.0%, respectively. CONCLUSION: Both the CM volume/MDRD and CM volume/eGFR(CyC) 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.