Safe contrast volumes for preventing contrast-induced nephropathy in elderly patients with relatively normal renal function during percutaneous coronary intervention.

The aim of this study was to evaluate contrast media volume to creatinine clearance (V/CrCl) ratio for predicting contrast-induced nephropathy (CIN) and to determine a safe V/CrCl cut off value to avoid CIN in elderly patients with relatively normal renal function during percutaneous coronary intervention (PCI). We prospectively enrolled 1020 consecutive elderly patients (age ≥65 years) with relative normal renal function (baseline serum creatinine <1.5 mg/dL) undergoing PCI. Receiver operating characteristic (ROC) curves were used to identify the optimal cut off value of V/CrCl for detecting CIN. The predictive value of V/CrCl for CIN was assessed with a multivariate logistic regression. Thirty-nine patients (3.8%) developed CIN. There was a significant association between a higher V/CrCl ratio and CIN risk (P < 0.001). ROC curve analysis indicated that a V/CrCl ratio of 2.74 was a fair discriminator for CIN (C statistic = 0.68). After adjusting for other known CIN risk factors, V/CrCl ratios >2.74 remained significantly associated with CIN (odds ratio = 3.21, 95% confidence interval [CI] 1.45-7.09, P = 0.004) and worse long-term mortality (hazard ratio = 1.96, 95% CI 1.14-3.38, P = 0.016). A V/CrCl ratio >2.74 was a significant independent predictor of CIN and was independently associated with long-term mortality in elderly patients with relatively normal renal function.