Non-invasive diagnosis of non-alcoholic fatty liver disease. A critical appraisal

Non-alcoholic fatty liver disease (NAFLD) affects one in every three subjects in the occidental world. The vast majority will not progress, but a relevant minority will develop liver cirrhosis and its complications. The classical gold standard for diagnosing and staging NAFLD and assessing fibrosis is liver biopsy (LB). However, it has important sample error issues and subjectivity in the interpretation, apart from a small but real risk of complications. The decision to perform an LB is even harder in a condition so prevalent such as NAFLD, in which the probability of finding severe liver injury is low. In an attempt to overcome LB and to subcategorize patients with NAFLD in different prognoses allowing better management decisions, several non-invasive methods have been studied in the last decade. The literature is vast and confusing. This review will summarize which methods have been tested and how they perform, which tests are adequate for clinical practice and how they can change the management of these patients.