Hepatitis C and nonalcoholic fatty liver disease.

Hepatitis C virus (HCV) and nonalcoholic fatty liver disease (NAFLD) are the two most common causes of chronic liver disease in North America. NAFLD represents a spectrum of liver lesions that occur in individuals who either do not consume any alcohol or only consume alcohol in quantities generally considered not to be harmful to the liver. This spectrum consists of isolated hepatic macrovesicular steatosis at one end and nonalcoholic steatohepatitis (NASH) at the other. Hepatic steatosis is present in approximately 50% of the subjects with HCV. Genotype 3 is independently associated with hepatic steatosis. In those with genotype 1 infection, steatosis is associated with features of the metabolic syndrome. The presence of hepatic steatosis correlates with the stage of hepatic fibrosis in patients with HCV. This has been related to the presence of insulin resistance. Hepatic steatosis also adversely affects the virologic response rates to anti-HCV therapy. In this article, we will review the epidemiology of HCV and NAFLD, their impact on each other, and the course of the liver disease in individuals afflicted with both conditions.