OBJECTIVES : Nonalcoholic steatohepatitis (NASH) is a progressive form of nonalcoholic fatty liver disease (NAFLD) and is characterized by excessive liver fat accumulation, inflammation, cell injury and fibrosis. There is a need to better estimate the prevalence of NAFLD and NASH. The aim of this literature review was to report the global prevalence of NAFLD and NASH.

METHODS : A targeted literature review was conducted using Embase and Medline (1985-2017) to identify key published studies reporting the epidemiology of NAFLD and NASH among adult general population (> RESULTS : Thirty studies with epidemiology data on NAFLD/NASH were identified across US, Europe and Asia. The reported prevalence of NAFLD among the general population ranged between 22%-37% (US: 22%-32%; Europe 29-37%; Asia: 29.7%). Biopsy-confirmed NASH was reported between 16%-70% among the NAFLD population (US: 42-68%; Europe 16-45%; Asia: 70%). Two US studies reported the prevalence of NASH amongst the general population (0.05%-0.7%) using ICD-9 (571.8)/10 codes connected to NASH, as a proxy. Among the identified studies, a variety of comorbidities were reported in the study populations; diabetes, obesity, hypertension. The reported prevalence of NASH amongst type 2 diabetic patients and obesity patients, ranged between 57%-64% and 14%-47%, respectively.

CONCLUSIONS : There is vast variability in the reported prevalence of NAFLD/NASH globally, however the findings are comparable to recently published meta-analyses. Although biopsy is considered the gold standard diagnosis for NASH, its limited use owing to associated procedural risks may not give us the true prevalence of NASH. Therefore, there is a need to achieve consensus in terminology, disease definition and diagnostic methods to better determine the true prevalence of the disease.