- Both pre- and postoperative cystatin C was significantly higher in the AKI group and positively correlated with postoperative creatinine (r = 0.38, p = 0.01; r = 0.68, p = 0.04, respectively). Preoperative cystatin C and CBP times of increase were independent predictors for AKI [63]. This evidence concerns the gene CST3 and acute kidney injury.