Clinical features and natural history of nonalcoholic steatosis syndromes

Nonalcoholic steatohepatitis, along with other forms of nonalcoholic fatty liver disease, is a chronic liver disease that is attracting increasing sig nificance. It is a clinicopathologic syndrome that was originally described in obese, diabetic females who denied alcohol use but in whom the hepatic histology was consistent with alcoholic hepatitis. This typical patient pro file has been expanded and is now recognized to occur even in normal weight males without overt abnormalities in carbohydrate metabolism. Although ori ginally believed to be a benign clinical entity, nonalcoholic steatohepatit is is now recognized as a cause of progressive fibrotic liver disease with adverse clinical sequelae. It is important to emphasize that nonalcoholic s teatohepatitis is best considered one type of a larger spectrum of nonalcoh olic fatty liver disease that is a consequence of insulin resistance and ra nges from fat alone to fat plus inflammation, fat plus ballooning degenerat ion, and nonalcoholic steatohepatitis, the latter being the most serious fo rm. As with any disease, the clinical importance of nonalcoholic steatohepa titis is related to its prevalence and natural history. Recent studies usin g different methodologies indicate that in the general population the preva lence of fatty liver and nonalcoholic steatohepatitis is approximately 20% and 3%, respectively. These prevalence rates are increased in certain subpo pulations such as obesity and type II diabetes. Of greater concern is the r ecognition that cirrhosis and liver-related deaths occur in approximately 2 0% and 8% of these patients, respectively, over a 10-year period. Risk fact ors for these adverse clinical symptoms include patients older than the age of 45, the presence of diabetes or obesity, an aspartate aminotransferase/ alanine aminotransferase ratio >1 and hepatic histology. However, a number of important unresolved issues must be clarified before the true natural hi story of this disease can be fully understood.