Nonalcoholic Fatty Liver Disease: Epidemiology, Assessments, and Interventions Entering 2021

NAFLD is an overarching disease inclusive of nonalcoholic fatty liver (liver fat in the absence of inflammation and fibrosis), nonalcoholic steatohepatitis (liver fat with varying degrees of inflammation and fibrosis [NASH]), and cirrhosis due to NASH.1 NAFLD is common in the United States and worldwide, with one-quarter to one-third of people having some degree of excess fat in the liver2,3 and up to 5% of the population having NASH.4 NAFLD in most cases is caused by the metabolic syndrome and can advance to end-stage liver disease and hepatocellular carcinoma. NAFLD cirrhosis is a leading cause of liver transplantation in the United States and represents a significant economic burden.5 Despite this, no therapies for NAFLD or NASH have been approved by the US Food and Drug Administration. MAFLD [metabolic associated fatty liver disease] likely represents the missing puzzle in majority of cases of progressive liver disease despite treatment of the underlying etiology of chronic liver disease, such as chronic hepatitis B or C infection.