Non-alcoholic fatty liver disease (NAFLD) is a major public health problem both in the Western world and in the East. This is mainly due to the high prevalence of the disease and its effects on the individual with NAFLD. In the USA, it is estimated that approximately a third of the general population has NAFLD. Increasing age, obesity and the presence of multiple features of metabolic syndrome, especially diabetes, are associated with a higher probability of having non-alcoholic steatohepatitis (NASH). In the individual with NAFLD, excess hepatic fat is associated with an increased risk of developing diabetes, hypertension, cardiovascular events, abnormal resting electrocardiography and endothelial dysfunction. These findings have been corroborated in studies in teenagers as well as adults. There is also an increase in cardiovascular mortality, especially in those with NASH. In addition, there is an increased risk of death from a variety of non-hepatocellular cancers. From a liver perspective, NAFLD is associated with a 15-20% risk of progression to cirrhosis. The disease progresses more rapidly in those with diabetes, increasing age and obesity. The PNPLA3 gene mutation at position 148 is associated with not only steatosis, but with the likelihood of having steatohepatitis and increased inflammation and fibrosis. Once cirrhosis develops, the liver disease decompensates at the rate of 3-4% per year. NASH-related cirrhosis is a risk factor for hepatocellular cancer. All of these factors indicate that NAFLD is a common condition that has significant adverse health consequences for those who are afflicted. It is therefore a major public health hazard throughout the world.
© 2011 The Japan Society of Hepatology.