The diagnostic and predictive value of plasma cystatin C for acute kidney injury secondary to sepsis in the intensive care unit

Abstract

Introduction : Plasma Cystatin C (pCysC) is one of the functional biomarker for Acute Kidney Injury (AKI). Derivation of estimate of Glomerular Filtration Rate (eGFR) from pCysC has been developed for practical daily use in clinical practice for evaluating renal function. This study evaluates the utility of pCysC in diagnosing AKI, predicting death and its correlation with eGFR in septic critically ill patients. Materials and method : This is a two centre, prospective observational study of septic critically ill patients. Inclusion criteria were patients older than 18 years old with sepsis, based on Sequential Organ Failure Assessment (SOFA) score of two or more and procalcitonin level greater than 0.5 ng/ml. Serum Creatinine and pCysC were measured at six time intervals (0, 4, 24, 28, 48, and 52 hours). AKI was defined based on creatinine criteria of the Kidney Disease : Improving Global Outcome (KDIGO) guideline. Result : Seventy patients were recruited into this study, of which 32 (45.7%) had AKI and 15 (21.4%) died. pCysC diagnosed AKI in all six time intervals with AUC range of 0.859, 0.858, 0.876, 0.918, 0.887, and 0.879 for 0 hour, 4, 24, 28, 48, and 52 hours, respectively (p <0.0001). It did not predict in-hospital mortality at any time interval, with AUC range of 0.053 to 0.608 (p >0.1). pCysC showed strong negative correlation with all estimates of GFR, with best profile recorded at 28 hours. Correlation coefficient for eGFRCG, eGFRMDRD, eGFRCKD-EPI and keGFR were -0.778, -0.763, -0.808, and -0.781, respectively (p <0.0001). There is no correlation between cardiac output and pCysC and GFR. Correlation coefficient were between -0.208 to 0.267 (p >0.1) Conclusion : Plasma Cystatin C diagnosed AKI in septic critically ill patients and strongly correlated with all estimates of GFR. However, plasma Cystatin C did not predict in-hospital death. In addition, it did not correlate with cardiac output.