Alternative definition of acute kidney injury following liver transplantation: Based on serum creatinine and cystatin C levels

Objective. The aim of this study was to verify the estimation and the predictive abilities of serum creatinine (Cr), serum cystatin C (Cys C), and related formulas for acute kidney injury (AKI). Patients and Methods. Thirty patients who underwent cadaveric donor liver transplantation were enrolled in this prospective study. Glomerular filtration rate (GFR) was assessed by the Tc-99m DTPA clearance method and estimated by Cr-predicted clearances (Cockcroft-Gault method [CG] and abbreviated Modification of Diet in Renal Disease equation [MDRD]) as well as by 3 other Cys C-based formulas (Hoek, Filler, and Larsson). AKI was confirmed as GFR < 80 mL/min/1.73 m(2) in the first posttransplantation week. Results. GFR was significantly correlated with reciprocal Cr, reciprocal Cys C, and the 5 formulas (P < .001 for all). The receiver operating characteristic (ROC) area of Cys C was larger than that of Cr (.937 vs .794, P < .05). ROC area of Hoek, or Filler or Larsson was also larger than that of CG or MDRD (.937, .935, .937 vs .802, .849, P < .05 for all). ROC analysis showed the cutoff values were 1.0 mg/dL for Cr and 1.57 mg/L for Cys C. Hoek, Filler, and Larsson equations all underestimated AKI; their optimal cutoff values should be adjusted to 47, 56, and 44 mL/min/1.73 m(2), respectively. Conclusion. Cys C is a better predictor of AKI than Cr. A value of more than 1.57 mg/L might be considered a new definition of AKI.