Pediatric Nonalcoholic Fatty Liver Disease: A Report from the Expert Committee on Nonalcoholic Fatty Liver Disease (ECON)

Abstract

Fatty liver disease in children has been increasingly recognized as an important pediatric health problem over the last 2 decades. Obesity is strongly associated with nonalcoholic fatty liver disease (NAFLD), with high rates of NAFLD reported among obese cohorts, and even higher rates among morbidly obese adolescents. 1,2 Data from multiple sources, including the US National Health and Nutrition Examination Survey (NHANES), suggest the overall prevalence of children suspected to have NAFLD has more than doubled in the last 2 decades. 3-5 The prevalence of pediatric NAFLD may be as high as 9.6% in the general population, 6 and NAFLD is now the most common cause of chronic pediatric liver disease in the developed world and is increasing in prevalence across the developing world as well. 7-11 The primary care provider is at the forefront of this epidemic of childhood obesity and will see many children at risk for NAFLD. Given their frontline status, the primary care provider has the potential to both detect and intervene in the natural history of childhood NAFLD. NAFLD is not a single entity but reflects a series of disease states across a spectrum of severity. These distinctions have been established based on histologic definitions wherein NAFLD is the umbrella diagnosis, with a threshold of macrovesicular steatosis being present in $5% of hepatocytes, and nonalcoholic steatohepatitis (NASH) is the severe subset of patients on the NAFLD spectrum wherein the liver histology has inflammation and cellular injury with or without fibrosis in addition to the steatosis. 12 The long-term prognosis for children with NAFLD is determined by the liver histology at diagnosis; specifically, whether they have the mildest form (isolated hepatic steatosis) or the more severe form, NASH. These distinctions are not merely semantics, as NASH-related fibrosis can progress to cirrhosis as early as childhood. 13 We now understand that all-cause mortality and liver transplant free survival are different in patients with NASH compared with individuals with steatosis alone or the non-NAFLD background population. 14,15 Over the pastdecade, thescientificcommunityhas garneredstrongevidence implicating NASH as a key contributor in the development and severity of extrahepatic comorbidities of the metabolic syndrome. 16-19 Under the guidance of the North American Society’s Pediatric Gastroenterology Hepatology and Nutrition Foundation’s NAFLD initiative, we constituted an expert group of pediatric gastroenterologistsfromacrossthe USand Canada with acommonresearch andclinicalfocusinNAFLD.Theauthorsofthisreport areall members of this Expert Committee on NAFLD and aim to provide the readership insight into recent advances in the field of pediatric NAFLD, dispel common misconceptions regarding the use of alanine aminotransferase (ALT) in NAFLD, and highlight existing knowledge gaps in identification and assessment of children with NAFLD, as well as research. Thecontentsofthisreport donotrepresenttheofficial guidelines of North American Society for Pediatric Gastroenterology, Hepatology and Nutrition.