AST ratio (expressed as a number of times normal) to the platelet count (109/L). The obvious advantage is simplicity, availability, and “free”. 0.88 and 0.94 for the diagnosis of significant fibrosis and cirrhosis, respectively. The thresholds retained for the diagnosis of significant fibrosis are < 0.5 (negative predictive value 86%) and > 1.5 (positive predictive value 88%). This made it possible to classify only 51% of the patients. The thresholds for cirrhosis are < 1 and > 2 and this classified 81% of patients. the negative and positive predictive values for the diagnosis of significant fibrosis are 75% and 77% respectively. Performance is better for excluding cirrhosis (negative predictive value of a score < 1 = 91%). Overall, significant fibrosis could be excluded in 30% of patients and cirrhosis in 75% of patients. The use of this score alone in less targeted populations risks suffering from the lack of specificity of these two markers which experience many other variations than those observed in chronic liver pathologies (alcohol, drugs, blood diseases, cardiac and muscular disorders, etc.).
Hepatic fibrosis corresponds to an excessive deposit of extracellular matrix in the liver parenchyma. To a quantitative anomaly is added a qualitative anomaly since the composition of this matrix is also disturbed. If the mechanisms of fibrogenesis involved are common to all hepatopathies, there are differences in particular for the distribution of fibrosis according to the etiologies. For example, fibrosis would begin in the centrilobular region for toxic or vascular causes and in the portal region for viral causes. At any time, this fibrous state is the result of a balance between the mechanisms of synthesis, deposition, and degradation of the components of the matrix. In perpetual remodeling, this process is also dynamic over time, which makes it insufficient to assess fibrosis at a time. We can, for example, make the hypothesis that it is preferable to be at a Fib2 stage of fibrosis in the process of regression than at a Fib1 stage of fibrosis in the process of worsening. This introduces the need for repeat assessments which is difficult to apply to liver biopsy.