Nonalcoholic Fatty Liver Disease: Epidemiology, Liver Transplantation Trends and Outcomes, and Risk of Recurrent Disease in the Graft

In parallel with the rising prevalence of metabolic syndrome globally, nonalcoholic fatty liver (NAFL) disease is the most common chronic liver disease in Western countries and nonalcoholic steatohepatitis (NASH) has become increasingly associated with hepatocellular carcinoma. Recent studies have identified NASH as the most rapidly growing indication for liver transplantation (LT). As a hepatic manifestation of the metabolic syndrome, NAFL disease can be histologically divided into NAFL and NASH. NAFL is considered a benign condition, with histological changes of hepatocyte steatosis but without evidence of hepatocellular injury or fibrosis. This is distinct from NASH, which is characterized by hepatocyte ballooning and inflammation, and which can progress to fibrosis and cirrhosis, hepatocellular carcinoma, and liver failure. As for any other end-stage liver disease, LT is a curative option for NASH after the onset of decompensated cirrhosis or hepatocellular carcinoma. Although some studies have suggested increased rates of sepsis and cardiovascular complications in the immediate postoperative period, the long-term posttransplant survival of NASH cases is similar to other indications for LT. Recurrence of NAFL following LT is common and can be challenging, although recurrence rates of NASH are lower. The persistence or progression of metabolic syndrome components after LT are likely responsible for NASH recurrence in transplanted liver. Therefore, while maintaining access to LT is important, concerted effort to address the modifiable risk factors and develop effective screening strategies to identify early stages of disease are paramount to effectively tackle this growing epidemic.