Serum Cystatin C as a predictor of cardiac surgery associated-acute kidney injury in patients with normal preoperative renal functions. A prospective cohort study

Introduction: Cardiac surgery-associated acute kidney injury (CSA-AKI) remains a known complication, where postoperative (PO) Cystatin C (Cys C) has been shown to be an earlier marker than the relatively late appearing creatinine (Cr). We sought to evaluate the reliability of preoperative (pre-OP) Cys C as a predictor for CSA-AKI in patients with normal renal functions. Methodology: Our study included consecutive patients undergoing on-pump cardiac surgery from July 2011 to April 2012. Pre-OP and PO Cystatin C and renal profiles were compared in AKI (GP I) and non-AKI (GP II) patients. RIFLE and AKIN criteria were calculated at baseline and daily during the successive three PO days. Results: Out of 40 patients (16 males; mean age = 59 years), 20 developed AKI. Both Pre- and PO Cys C were significantly higher in GP I, and positively correlated with PO Cr. (r: 0.38 P; 0.01; r: 0.68, p 0.04 respectively). Using ROC curve, a cutoff value of 1.8 mg/l and 1.88 (sensitivity 50 and 80%; specificity 90 and 65%) for Pre-OP and PO Cys C respectively in predicting AKI. Multivariate analysis showed the Pre-OP Cys C and cardiopulmonary bypass time were independent predictors for AKI. Conclusion: In patients with apparently normal renal functions, preoperative Cys C may be a predictor of post cardiac surgery AKI. In those patients, especially diabetics, Cys C may uncover subtle nephropathy which makes them more prone to AKI posed by stresses of cardiac surgery. (C) 2017 The Egyptian College of Critical Care Physicians. Production and hosting by Elsevier B.V.