Noninvasive tests (NITs) have been developed as an alternative to invasive liver biopsy, the current gold standard for non-alcoholic steatohepatitis (NASH) diagnosis and hepatic fibrosis stage identification. The use of NITs in clinical practice should facilitate the early diagnosis of high-risk non-alcoholic fatty liver disease (NAFLD).
Most NITs have not been fully validated for the diagnosis of NASH. However, considerable efforts have been invested into developing NITs for fibrosis. These can be divided into three categories: clinical tools tasked with calculating a fibrosis risk score (e.g., Fibrosis-4 index (FIB-4), NAFLD Fibrosis Score (NFS)); imaging technologies which measure liver stiffness (e.g., transient elastography (TE)); and blood-based hepatic fibrosis biomarkers (e.g. the Enhanced Liver Fibrosis (ELF) test).
The aim of this article was to assess the validity of NIT use and genetic testing for the diagnosis of NASH and advanced fibrosis. To do so, a panel of 9 NASH experts summarised the evidence supporting a series of 7 Clinical Assertion Statements regarding NIT use in NASH diagnosis and management, which were developed by the forum chairs. A level of acceptance of each Statement was then voted upon by the expert panel, according to the evidence presented.
The panel’s experts reached a consensus regarding the importance of NITs in the evaluation of NAFLD patients. They further emphasised the critical role of blood-based NITs in assessing fibrosis in this patient population.
The experts also agreed that a diagnosis of advanced fibrosis or cirrhosis should not rely on one NIT in the absence of compelling laboratory data signalling cirrhosis. Clinicians should become familiar with the use of NIT combinations, specifically blood-based NITs and TE, to enhance the assessment of fibrosis. This is particularly relevant in cases where one NIT indicates an ambiguous result, or when two NITs yield different results.
Furthermore, they indicated that histologic evidence of NASH delivered via liver fibrosis should not be a prerequisite for the initiation of pharmacologic therapy in patients who have been diagnosed with moderate or advanced fibrosis by NITs. Additionally, fibrosis progression should be examined using period elastograhy-based monitoring at intervals tailored to each patient.
Lastly, the experts found that genetic testing for potential genetic markers (e.g., PNPLA3) associated with NAFLD would not be useful at present in its clinical management but should be a priority for future research.