PHILADELPHIA — Nonalcoholic fatty liver disease is emerging as a major health burden in the United States, Dr. K. Rajender Reddy said at the annual meeting of the American College of Physicians.
Often associated with obesity and underlying insulin resistance, nonalcoholic fatty liver disease (NAFLD) is believed to affect as much as 20%–30% of the U.S. population, said Dr. Reddy, professor of medicine and surgery and director of hepatology at the University of Pennsylvania, Philadelphia.
There is some debate about the amount of alcohol ingestion permitted to make the distinction between alcoholic steatosis and NAFLD, which is defined as increased liver weight by 5%–10% as a result of fat accumulation (steatosis), in the absence of excessive alcohol consumption.
Most experts agree, however, that overall alcohol consumption of less than 20 g per day is well below that which would be associated with significant alcoholic liver disease, noted Dr. Reddy, who is also medical director of liver transplantation at the university.
Classification of NAFLD falls into four types: Type 1 (fatty liver alone) and type 2 (fat accumulation and lobular inflammation) are considered to be NAFLD alone. The more serious types 3 (fat accumulation and ballooning degeneration) and 4 (fat accumulation, ballooning degeneration, and either Mallory hyaline and/or fibrosis) are characterized as nonalcoholic steatohepatitis (NASH).
“There is a tendency to use the term NASH loosely in everyone who has nonalcoholic fatty liver disease. You should use the general term NAFLD and reserve NASH only for those who have histologic evidence of steatohepatitis,” Dr. Reddy advised.
Overall, about 10% of patients with NAFLD have NASH. Limited data on the natural history of these conditions suggest that about 15%–20% of patients with steatosis will progress to steatohepatitis at some point. Of those, smaller numbers will go on to develop fibrosis, cirrhosis, and hepatocellular carcinoma. The exact percentages have varied widely in different studies.
Factors that predict progression from NAFLD to NASH include age greater than 45 years, type 2 diabetes, body mass index greater than 35 kg/m
Data pertaining to treatment of NAFLD are also limited, but weight management is considered a major priority for all patients because of proven benefits in cardiovascular risk profile.
Overall, about 10% of patients with nonalcoholic fatty liver disease have nonalcoholic steatohepatitis. DR. REDDY