Non-alcoholic fatty liver disease (NAFLD) is currently the most common form of chronic liver disease in both children and adults and threatens to become a serious public health problem worldwide.1 2 It is closely associated with obesity and insulin resistance and encompasses a spectrum of disease ranging from simple fatty liver (steatosis), through necroinflammation to fibrosis and cirrhosis,3 Despite its undoubted importance, perhaps surprisingly, to date there is a paucity of data on the change in prevalence of NAFLD within a population over time, and no convincing data on either the incidence of NAFLD, or on the long-term survival of children with NAFLD.

This latter gap in the literature has now been partly filled by the study by Feldstein and colleagues4, published in this issue of Gut (see page 1538), which describes the long-term outcomes and survival of children with NAFLD followed up for 20 years. The strength of the conclusions arising from the study is limited by its retrospective design, the low number of patients undergoing liver biopsy (7.5%) and …