Factors influencing renal function after liver transplantation. Results from the MOST, an international observational study.

INTRODUCTION: Renal failure, both acute and chronic, is a common complication after liver transplantation and can seriously jeopardise long-term outcome. Given organ shortage it should be essential to determine which patients will experience progressive and severe renal dysfunction after liver transplantation (LT).

AIM: To correlate pre-transplant renal function and risk factors for renal failure after liver transplantation with occurrence of renal failure at 1 and 5 years after LT, with particular attention to hepatitis C virus (HCV) infection.

METHODS: Data from patients enrolled in the liver section of Neoral MOST (Multinational Observational Study in Transplantation) study were used for the analysis. HCV status, pre-transplant serum creatinine level, recipient gender, recipient age, pre-transplant arterial hypertension, pre-transplant diabetes mellitus, pre-transplant antiviral therapy, the time of the transplant (before or after 2000) and immunosuppressive regimen were collected for each patient. Post-transplant occurrence of renal failure at 1 and 5 years was defined as a GFR<60 mL/min/1.73 m(2) (Stage III of the National Kidney Foundation).

RESULTS: Data from 1948 patients enrolled in the study were considered. Glomerular filtration rate (GFR) was evaluated in 406 patients at 1 year and in 233 patients at 5 years after LT. The prevalence of HCV infection was 35% in the former and 37% in the latter. The median GFR was 70 mL/min/1.73 m(2) after 1 year and 69 mL/min after 5 years, significantly lower in HCV-positive (HCV+) than in HCV-negative (HCV-) patients both 1 and 5 years after LT (p<0.001). GFR before transplant correlated with GFR at 1 month, 1 and 3 years (p<0.0001 for all correlations). Multivariate analysis confirmed HCV status, pre-LT serum creatinine levels and recipient gender as significant predictors of 1-year GFR (p<0.001 for all three). Further analysis of the effect of recipient gender indicated that the only significant risk factor observed in both male and female patients was HCV positivity. Only 1-year GFR was an independent predictor of 5-year GFR (p<0.001). HCV+ status, cyclosporine (CsA) exposure, antiviral therapy and diabetes mellitus had no significant influence on 5-year GFR.

CONCLUSIONS: HCV status and pre-LT serum creatinine levels were independent predictors of renal function a year after LT, together with GFR before transplant. The negative impact of HCV positivity on renal function was not confirmed in the long term, whereas the prognostic influence of an abnormal renal function in the early post-transplant period was more persistent.