Transient Hepatic Elastography in the Assessment of Liver Fibrosis in Patients After Liver Transplantation

Abstract

Introduction and Objectives. Liver biopsy is the gold standard for assessing fibrosis and inflammation in liver transplant recipients. As this study has risks, the use of noninvasive tools has been proposed, including transient elastography, a method that needs further study in this population, which is the purpose of this research. Material and methods. Demographic and clinical data were collected retrospectively in patients who received a liver transplant, underwent liver biopsy and transient elastography less than 1 year apart. Sensitivity, specificity, diagnostic accuracy and Kappa concordance test between the two methods were determined. Results. Of 356 patients evaluated after transplantation, 45 underwent liver biopsy and transient elastography within 1 year; 60.0% were male and 75.6% had hepatitis C virus infection. At the time of transient elastography, laboratory values were: mean total bilirubin 1.5 mg/dL, alanine aminotransferase 108.1 U/L, aspartate aminotransferase, 101.6 U/L, alkaline phosphatase, 96.0 U/L and gamma-glutamyl transferase 9.0 U/L. The main indications for liver biopsy were assessment for rejection, hepatitis C virus infection or both. According to liver biopsy, 82.2% presented absent or minimal fibrosis and 75.6% had no inflammation. Acute cellular rejection was present in 20.0% of cases. A cut-off point of > 9.5 kPa was used to define advanced fibrosis, while a value < 7.5 kPa was set to indicate absent or mild fibrosis. Poor agreement was found between transient elastography and liver biopsy for these categories (Kappa 0.125, sensitivity 69.5%, specificity 66.7%) and for specific stages of fibrosis (Kappa 0.095). Conclusions. Accuracy, sensitivity and specificity were low for fibrosis staging when comparing transient elastography with liver biopsy. In liver transplant recipients, transient elastography would overestimate fibrosis, probably due to inflammation secondary to other causes.