Urinary interleukin-18 as an early indicator to predict contrast-induced nephropathy in patients undergoing percutaneous coronary intervention

Contrast-induced nephropathy (CIN) is at present the third leading cause of hospital-acquired acute kidney injury (AKI). Traditionally, it is diagnosed by measuring an increase of the serum creatinine (SCr) concentration. However, SCr is an insensitive marker for detecting CIN. This study was designed to investigate whether human urinary interleukin-18 (IL-18) is early predictive marker for CIN following coronary interventional procedures. The general clinical data of 180 patients who underwent coronary interventional procedures at the Department of Cardiology, Affiliated Hospital of Xuzhou Medical College from March 1, 2012 to September 31, 2012 were collected. A nonionic, low osmolality contrast agent was used in the laboratory at this time. SCr values and estimated glomerular filtration rate (eGFR) were measured prior to and within 24 and 48 h after the administration of contrast agents. Urine samples were collected prior to and 2, 6, 12,24 and 48 h after the coronary interventional procedure, and urinary IL-18 levels were measured using an ELISA kit. CIN was defined as an increase of >= 0.5 mg/dl or >= 25% in SCr concentration over baseline 24-48 h after the procedure. CIN occurred in 16 of 180 (8.9%) patients. The levels of urinary IL-18 measured 2 h after the procedure were increased in the CIN group, but the increase was not significant (P>0.05). There were significant differences (P<0.05) between the urinary IL-18 levels 6, 12, 24 and 48 h after the procedure and those before the procedure. No significant difference was identified between the SCr levels measured prior to and 24 h after the procedure. The area under the receiver operating characteristic (ROC) curve of urinary IL-18 12 h after the procedure was 0.811 and the 95% confidence interval of the area under the curve was 0.735-0.888. If the critical point of the diagnosis of CIN was 815.61 pg/ml, the sensitivity was 87.5% and the specificity was 62.2%. Univariate analysis indicated that the urinary IL-18 level was positively correlated with the SCr concentration pre- and postprocedure. In conclusion, urinary IL-18 may be a promising indicator for the early prediction of CIN.