Definition and natural history of metabolic steatosis: clinical aspects of NAFLD, NASH and cirrhosis

Metabolic steatosis or non-alcoholic fatty liver (NAFLD) is the most common cause of chronic liver injury in Western countries. Histological signs of necroinflammation, indicating the presence of non-alcoholic steatohepatitis (NASH), are present in 20-30% of cases. While steatosis on its own has a benign course, NASH may be associated with fibrosis and may progress to cirrhosis, terminal liver failure and hepatocellular carcinoma. NAFLD is closely associated with the metabolic syndrome, its prevalence reaching 50-90% in obese patients. The clinical impact of NAFLD has been demonstrated in large cohort studies by the overprevalence of cirrhosis and hepatocellular carcinoma in obese and diabetic patients. In terms of survival, liver disease is the third most common cause of mortality in patients with NAFLD. When associated with other causes of liver disease such as alcohol consumption or hepatitis C infection, metabolic steatosis may be a major risk factor for disease progression. (C) 2008 Elsevier Masson SAS. All rights reserved.