Non-alcoholic fatty liver disease: epidemiology, clinical course, investigation, and treatment.

BACKGROUND: The global obesity epidemic has increased the prevalence of fatty liver disease. At present, 14% to 27% of the general population in the industrialized world has non-alcoholic fatty liver disease (NAFLD).

METHOD: We review pertinent publications retrieved by a selective search of the PubMed database for the years 1995 to 2013.

RESULTS: The term "non-alcoholic fatty liver disease" covers cases of a wide spectrum of severity, ranging from bland fatty liver without any inflammation and with little or no tendency to progress all the way to non-alcoholic steato-hepatitis (NASH) with inflammatory reactions and hepatocyte damage, with or without fibrosis. Some 5% to 20% of patients with NAFLD develop NASH, which undergoes a further transition to higher-grade fibrosis in 10% to 20% of cases. In fewer than 5% of cases, fibrosis progresses to cirrhosis. These approximate figures lead to an estimate of 0.05% to 0.3% for the prevalence of cirrhosis in the general population. About 2% of all cirrhosis patients per year develop hepatocellular carcinoma. The diagnosis of fatty liver disease can be suspected initially on the basis of abnormally high aspartate aminotransferase (ASAT) and/or alanine aminotransferase (ALAT) levels and abnormal ultrasonographic findings. The positive predictive value of an ultrasonographic study for mild steatosis is 67% at most. The NAFLD fibrosis score, which is computed on the basis of multiple parameters (age, body-mass index, diabetes status, ASAT, ALAT, platelet count, and albumin level), has a positive predictive value of 82% to 90% and a negative predictive value of 88% to 93%. Liver biopsy is the gold standard for diagnosis but should be performed sparingly in view of its rare but sometimes life-threatening complications, such as hemorrhage. The treatment of NAFLD and NASH consists mainly of changes in lifestyle and nutrition.

CONCLUSION: NAFLD can, in principle, be reversed. This is only possible with weight reduction by at least 3% to 5%.