Epidemiology of Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis: Implications for Liver Transplantation

Nonalcoholic fatty liver disease (NAFLD) affects 25% of the global adult population with a range of 13.5% in Africa and 31.8% in the Middle East. Nonalcoholic fatty liver disease is closely associated with a constellation of metabolic comorbidities which include: obesity, type 2 diabetes mellitus, hypertension, and hypercholesteremia. In fact, the increasing number of metabolic comorbidities not only increases the prevalence of NAFLD but also places patients at higher risk for progressive liver disease. As such, NAFLD is presently among the top etiologies for hepatocellular carcinoma and an indication for liver transplantation (LT) in the United States. Therefore, the following recommendations are made based on our current knowledge of NAFLD and its consequences: (1) the evaluation of the risk of liver disease progression can be affected by patient's ethnic origin and sex; (2) fibrosis in NAFLD is the most important predictor of mortality; (3) we recommend that individuals who present with features of metabolic syndrome in the presence of elevated liver enzymes should be screened for NAFLD and, more importantly, nonalcoholic steatohepatitis (NASH); (4) we recommend that NAFLD patients, especially those with multiple risk factors, should be screened for cardiovascular diseases and managed accordingly; (5) comorbidities in NAFLD/NASH patients who are considered for LT need to be assessed in the pretransplant and posttransplant settings because these factors can affect waitlist mortality, resource utilization, as well as posttransplant complications, morbidity, and perhaps, mortality; (6) any attempt to decrease the incidence of NAFLD should ideally address the development of obesity in childhood and early adulthood, favoring the adoption of healthy lifestyles through comprehensive health policy programs.