Introduction to fibrosis assessment by liver stiffness in different etiologies

Abstract

While mono-etiologic histology-proven cohort studies were instrumental in establishing cutoff values for histological fibrosis stages F0-F4, they differed drastically between liver diseases but also between even large studies of the same disease etiology. This has caused considerable confusion and many different cutoff values are circulating in the literature somehow preventing clear standards and an easier didactical access. It has been increasingly evident that the major reason of the different cutoff values seems to be caused by the various fibrosis-independent confounders of an elevated LS such as inflammation but also other, pressure related factors like cholestasis or congestion. In confirmation, treatment of various liver diseases whether it is alcoholic liver disease, autoimmune hepatitis, viral hepatitis, or NAFLD can result in up to 70% decrease of LS after resolution of inflammation. Likewise, standardization of patient cohorts e.g., with regard to inflammation also results in similar cutoff values. For simplification, it is therefore suggested to use general standard cutoff values for F0, F3, and F4 such as 6, 8, and 12.5 kPa as a rough first estimate. A refined approach is the usage of AST-adapted cutoff values for all forms of chronic hepatitis. In etiologies with continuous and constant presence of confounders such as chronic cholestatic liver diseases e.g., PSC or PBC, genuine cutoff values are applicable. The best fibrosis scoring is obtained after removing the confounder e.g., by treating the underlying disease and re-assessment of LS.