Risk factors for kidney impairment and differential impact of liver transplantation on renal function.

BACKGROUND: Chronic kidney disease (CKD) is a common problem in long-term survivors after liver transplantation (LT). It is important to identify and correct risk factors that negatively affect kidney function. The purpose of this study was to delineate the risk factors associated with progressive kidney dysfunction after OLT.
METHODS: We analyzed 50 recipients (10 female, 40 male) of overall age of 44±13 year who were all ≥18 years old and underwent first LT between 1999 and 2005. Patient-related risk factors were evaluated for renal failure at 3 and 5 years after transplantation. We evaluated parameters of demographic data, laboratory values, daily proteinuria, and renal resistive index (RRI) by Doppler ultrasonography. CKD was defined as a sustained decrease in estimated glomerular filtration rate (eGFR). Patients were divided into 3 groups according to the change in eGFR from the baseline value: group 1, stable eGFR (no change from baseline); group 2, <50% decreased eGFR; and group 3, ≥50% decrease from baseline. eGFR was calculated by using Modification of Diet in Renal Disease (MDRD) formula.
RESULTS: At 3 years after LT, GFR negatively correlated with initial Child-Pugh score (r=-0.42; P<.01); microalbuminuria (r=-0.28; P<.01), and RRI (r=-0.36; P<.01). After 5 years, GFR negatively correlated with initial gamma glutamyl transferase (r=-0.21; P<.05), PT (r=-0.29; P<.05), and RRI (r=-0.32; P<.01). Pretransplantation direct bilirubin levels were significantly correlated with GFR decrease at 3 years (P=.05). At 5 years of follow-up, smoking (P<.05), baseline alanine aminotransferase (P=.03) and serum triglyceride (P<.01) levels significantly correlated with eGFR decrease. Pretransplantation serum creatinine levels were stratified into normal versus high groups. Patients with increased basal serum creatinine levels displayed shorter survivals than those with normal creatinine levels, namely, median values of 21±3.9 months versus 14±2.4 months, log rank test: P<.05).
CONCLUSION: Renal function after liver transplantation show sustained impairment in certain patients. In the short term the main risk factors for renal detoriation were severity of liver disease before LT, microalbuminuria, and renal perfusion. In the long term, smoking and dyslipidemia were the main predictors of CKD. Patients with high basal serum creatinine values were at increased risk of mortality.