| Abstract
| - Background. As survival with an orthotopic liver transplant (OLT) improves, the incidence of chronic kidney disease in OLT recipients increases. Measurement of kidney function using creatinine-based estimates is often inaccurate, while cystatin C may overcome the biases that effect creatinine. The aim of this study was to assess the accuracy of creatinine- and cystatin C-based equations to estimate kidney function in long-term OLT recipients. Methods. This was a cross-sectional study performed on OLT recipients within a single liver transplant centre where creatinine (n = 41) and cystatin C (n = 30) were measured and glomerular filtration rate (GFR) estimated using the Modification of Diet and Renal Disease (MDRD), Cockcroft-Gault (CG), Hoek, Larsson, Filler and Le Bricon equations. Comparison was made with the nuclear GFR (nGFR) (n = 41) measured through 51-Cr EDTA clearance. Results. The mean age of recipients was 56 ± 13 years, and they were 6.5 ± 4.7 years post-OLT. Fifty-six percent of recipients had a nGFR ≤60 mL/min/1.73 m2. nGFR correlated significantly with all predictive equations (P< 0.001). The MDRD, CG and Le Bricon equations had the smallest degree of bias (−7.6, −7.3 and 3.4 mL/min/1.73 m2, respectively), with 22%, 22% and 27% of estimates, respectively, being within 10% of nGFR measurements. In OLT recipients with nGFR ≤60 mL/min/1.73 m2, the degree of bias of both the creatinine-base MDRD and cystatin-based Hoek equations was within 2 mL/min/1.73 m2 difference between the measured and estimated GFR, but 41% and 36% of estimates were within 10% of the nGFR measurement. Conclusions. Therefore, the degree of inaccuracy in cystatin C- and creatinine-based predictive equations brings into question their clinical utility in OLT recipients. We have no evidence that cystatin C is superior to creatinine in this population.
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