Improvement of Diagnostic Algorithm in Patients With Alcoholic Fatty Liver Disease by Using Non-invasive Methods of Verification of Liver Steatosis and Fibrosis

Introduction. Nonalcoholic fatty liver disease (NAFLD) is considered as one of the most common chronic liver diseases, and among the population of developed countries, this disease occurs in one of three middle-aged people. The aim of this study was to improve the diagnostic algorithm of NAFLD by assessing the capabilities of mod- ern non-invasive diagnosis of steatosis and fibrosis of the liver. Materials and methods. We used the content analysis, method of systematic and comparative analysis in studying the current 73 scientific studies published in English or Ukrainian (PubMed-NCBI, Medline, CochraneLibrary, EMBASE, ResearchGate), of which were selected 25 works which talked about the non-invasive methods of diagnosis with proven high sensitivity and specificity in diagnosis of NAFLD. The results of the analysis are highlighted in the tables. Several non-invasive methods aim at diagnosing and quantifying of hepatic steatosis, while others were designed to predict NASH or significant/advanced fibrosis. The search for the ideal non-invasive test has not been accomplished yet, which explains the vast number of tests available. Imaging techniques, biomarkers and complex models have been studied as tools to predict steatosis, NASH and fibrosis. New methods are usually compared with liver biopsy, that has accuracy far from perfect for NASH and even for fibrosis. For assessing steatosis, US may also be used as comparison, and US cannot detect mild steatosis. In that way, new methods can perform better than the gold standard leading to underestimation of the power of the test. The reliability and importance of the diagnostic tests depend on the disease, the population to which it is applied and the change in management induced by the test's result. A good screening test should have a high sensitivity even at expense of specificity, whereas a diagnostic test that selects patients for invasive procedures, therapy or clinical trials should have high specificity. Most methods have been evaluated in small pilot studies and have not been externally validated. The majority showed only suboptimal accuracy for NASH. Although discrimination for advanced fibrosis is usually reasonable, no test detects confidently mild/moderate fibrosis. Also, standardization of cut-offs is difficult and most methods lack reproducibility. For the time being, non-invasive tests do not replace liver biopsy, but may avoid it in a large number of cases with low probability or high-risk for having advanced fibrosis/cirrhosis. Ultrasonography still represents the first-line diagnostic tool for simple liver steatosis; its sensitivity could be enhanced by the complex biochemical score SteatoTest. Serum cytokeratin-18 is a promising and accurate non-invasive parameter for the diagnosis of non-alcoholic steatohepatitis (NASH). The staging of liver fibrosis still represents the most important prognostic problem: the most accurate estimating methods are FibroMeter, FIB-4, NAFLD fibrosis score and transient elastography. Conclusions. The calculation of certain clinical and laboratory indices can be used for diagnosis and quantification of the degree of liver damage in patients with NAFLD.