Epidemiology of a fast emerging disease in the Asia-Pacific region: non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is rapidly increasing in the Asia-Pacific and affects up to 30 % of the general population. In younger children, prevalence has been reported to be between 2.1 and 4.5 %. The prevalence of NAFLD increases with increasing age. NAFLD is more prevalent in men than women, but this trend fades in older age group. NAFLD is one of the most common causes of raised serum ALT levels and the latter is closely related to the presence of features of metabolic syndrome. NAFLD may contribute to metabolic syndrome in a similar way as visceral adiposity and can be an early predictor of metabolic disorders. NAFLD increases the risk of developing diabetes mellitus and is closely related to degree of glucose intolerance. A significant proportion of patients with NAFLD have impaired glucose tolerance or diabetes mellitus but with normal fasting blood glucose, highlighting the importance of oral glucose tolerance test in NAFLD patients with normal fasting blood glucose. Besides liver-related complications, NAFLD has been associated with cardiovascular complications, hyperuricemia, gout, chronic kidney disease, gallstone disease, colorectal adenomatous polyp, and polycystic ovarian syndrome. NAFLD seems to be related to host metabolic factors rather than viral factors and does not seem to affect severity of the liver disease in patients with chronic hepatitis B. On the other hand, hepatic steatosis may be related to both host metabolic and viral factors in patients with chronic hepatitis C and seems to adversely impact on the severity of liver disease and possibly response to antiviral therapy.