Prospective evaluation of cystatin C in the assessment of kidney dysfunction and survival in liver transplant candidates.

Abstract

Kidney dysfunction is associated with decreased survival in liver transplant (LT) candidates, yet serum creatinine (sCr) is a poor surrogate for glomerular filtration rate (GFR) in this population. Serum cystatin C (CysC) may provide a more accurate assessment of kidney function and predict outcomes. We performed a multicenter prospective cohort study of consecutive candidates for LT. CysC was obtained at LT evaluation (n = 244), and a subset underwent simultaneous I 125 -iothalamate clearance for measured GFR (mGFR) assessment (n = 137). Patients were followed to assess the need for pre-LT renal replacement therapy, simultaneous liver and kidney transplant, and survival. Estimated GFR (eGFR) based on MDRD-4, GRAIL, Royal Free Hospital Cirrhosis GFR, and the CKD-EPI equations was assessed for bias, precision, and accuracy in reference to mGFR. Receiver operator characteristic (AUROC) and competing risk survival analyses were performed. CysC more accurately discriminated mGFR than sCr at thresholds of ≤60 and ≤30 mL/min/1.73 m 2 with AUROC 0.92 ( p = 0.005) and 0.96 ( p =0.01), respectively. All eGFR equations overestimated GFR, especially among females ( p < 0.05). The GRAIL equation demonstrated the least bias, while CKD-EPI-cystatin C was associated with the greatest precision and lowest frequency of GFR overestimation. Among 165 recipients of LT, CysC discriminated pre-LT renal replacement therapy and the need for simultaneous liver and kidney transplant with AUROC of 0.70 and 0.85, respectively. Cumulative incidence of death, accounting for LT as a competing event, increased with CysC ( p = 0.002) but was not observed with sCr overall or among subgroups ( p = NS). CysC more accurately predicts thresholds of mGFR than sCr in candidates for LT. Elevated CysC discriminates pre-LT renal replacement therapy and simultaneous liver and kidney transplant and is strongly associated with survival in contrast with sCr. CysC is a promising tool to improve prognostication among candidates for LT.