Noninvasive means of diagnosing liver fibrosis in hepatitis C

Abstract

Liver biopsy is still considered the gold standard for staging fibrosis in chronic liver diseases. However, liver biopsy is an invasive procedure, and complications occur in 0.6%-5% of patients [1,2]. In addition, to perform the procedure there is a need for additional resources such as ultrasonography. Therefore, as a rule, patients undergoing liver biopsy are hospitalized for at least 6 hours [3]. Recent studies involving patients with chronic hepatitis C showed that fragments of technically inadequate hepatic tissue frequently lead to the underestimation of the stage of liver fibrosis [4]. That rate of diagnostic error can vary from 10%-30% depending on the study [5]. In addition, in developed countries, there is greater patient resistance to undergoing biopsy. In Brazil, there is an additional factor, which is that patients are obligated to submit to liver biopsy for indication of treatment, except in clinically confirmed cases of hepatic cirrhosis according to the Ministry of Health guidelines. For all of these reasons, an increasing number of studies are being conducted in order to evaluate the effectiveness of noninvasive markers for staging liver fibrosis. The noninvasive methods used in the largest number of published studies are the calculation of two indices the aspartate aminotransferase (AST) to platelet ratio index (APRI) and the FibroTest index and the FibroScan test. The effectiveness of the various methods evaluated in various studies revealed quite heterogeneous results. The APRI method and the Forns index are unable to stage a large percentage of patients, and their accuracies do not exceed 80%-85%. Therefore, a considerable number of patients are required to undergo liver biopsy. Otherwise, approximately 20% would be incorrectly diagnosed. The efficacy of those methods encounters difficulty regarding standardization and the definition of cut-off values for each degree of fibrosis.