Proteinuria and reduced estimated glomerular filtration rate are independent risk factors for contrast-induced nephropathy after cardiac catheterization

Background: The aim of this study was to investigate the incidence of contrast-induced nephropathy (CIN) according to renal function in patients with or without proteinuria after cardiac catheterization in Japan. Methods and Results: We conducted a multicenter prospective observational study involving 27 hospitals from all over Japan, which enrolled 906 patients with cardiac catheterization. CIN was defined as increase in serum creatinine ≥0.5 mg/dl or ≥25% from baseline between 48 and 72 h after exposure to contrast. The incidence of CIN in patients with estimated glomerular filtration rate (eGFR) <30 ml/min/1.73 m² was significantly higher than that in patients with eGFR ≥60 ml/min/1.73 m². In patients without proteinuria, the incidence of CIN did not increase as eGFR decreased, but such a trend was observed in patients with proteinuria. Proteinuria was highly significantly associated with CIN in patients with eGFR 30–44 ml/min/1.73 m² (OR, 12.1; 95% CI: 2.81–82.8; P=0.0006) and eGFR <30 ml/min/1.73 m² (OR, 17.4; 95% CI: 3.32–321; P=0.0001). On multivariate logistic regression analysis, proteinuria (OR, 4.09; 95% CI: 1.66–10.0), eGFR (OR, 1.02; 95% CI: 1.00–1.04), contrast volume/eGFR (OR, 1.31; 95% CI: 1.04–1.65), and Ca antagonist use (OR, 3.79; 95% CI: 1.52–10.8) were significant predictors of CIN. Conclusions: Proteinuria and reduced eGFR are independent risk factors for CIN after cardiac catheterization.