Feasibility of Using eGFR to Diagnose Contrast-Induced Nephropathy in Patients Undergoing Coronary Angiography

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Background: Contrast-induced nephropathy (CIN) is one of the common complications of coronary angiography (CAG). The changes of serum creatinine (Scr) before and after angiography were used to diagnose CIN in the world. But Scr is not a sensitive index to reflect early renal dysfunction. Estimated glomerular filtration rate (eGFR) is a comprehensive indicator to evaluate renal function but does not have accepted standard to diagnose CIN till now. This study aimed to investigate the feasibility of using eGFR to diagnose CIN in patients undergoing CAG. Methods: We included 300 coronary heart disease (CHD) patients who underwent CAG. Their demographics and basal renal function were recorded. Changes of Scr and eGFR before and after CAG were compared at the same time. Logistic regression was used to find independent influence factors of CIN. Receptor operating characteristic (ROC) curve was used to find the optimum cut-off value of eGFR for diagnosing CIN. Results: Among 300 patients with CHD, 64 (41 males and 23 females) of them were affected by CIN after CAG, with a total incidence of 21.3%. Among 271 patients whose Scr were normal (< 133 μmol/L) before CAG, 109 (40.2%) of them with impaired eGFR (< 90 ml/min/1.73m²). Patients had normal eGFR before CAG were less likely to develop CIN than those with normal Scr (15.4% vs 20.7%, P < 0.05). Logistic regression analysis showed that men, diabetes, multivessel lesion and eGFR were independent factors of CIN. ROC curve showed that the optimum cut-off value for diagnosing CIN was eGFR decrease by 22.5% after CAG (sensitivity = 98.4%, specificity = 98.3%, AUC = 0.973, 95%CI: 0.942-1.000, P = 0.000). Conclusions: eGFR is an independent factor of CIN, which is more sensitive than Scr in reflecting early renal dysfunction. Using eGFR to diagnose CIN is feasible in the clinic, but the cut-off value still needs to be confirmed by large scale clinical trials.