Review article: the epidemiologic burden of non-alcoholic fatty liver disease across the world

Background The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing in parallel to obesity and type 2 diabetes mellitus epidemics. Aim To provide a narrative review on NAFLD global epidemiology. Methods We retrieved articles from PubMed using search terms of NAFLD, epidemiology, prevalence, incidence, and comorbidities. Results Over 250 articles were reviewed. In 2016, the global NAFLD prevalence was 25%; this increased to >30% in 2019. The NAFLD prevalence in Asia, Latin America and Middle East-North Africa (MENA) was 30.8%, 34.5% and 42.6%, respectively. These prevalence rates increased with age. Although the NAFLD prevalence is higher in men, the prevalence rates for post-menopausal women are similar. NAFLD prevalence is higher in certain subpopulations, especially among the obese and those with metabolic syndrome (MS), while the prevalence of lean NAFLD is 11.2%. The global prevalence of non-alcoholic steatohepatitis (NASH) is estimated between 2% and 6% in the general population. Approximately 7% of NAFLD patients have advanced fibrosis but with rates between 21% and 50% among NASH patients. Overall mortality related to NAFLD is 15-20 cases per 1000 person-years, and increases substantially in NASH patients, especially with components of MS. Recent data suggest mortality/morbidity from NAFLD is increasing globally but NAFLD awareness remains low among patients and healthcare providers. Conclusions NAFLD poses a global public health problem with a very high disease burden in Asia, MENA and Latin America. Research is needed to better quantify the full impact of NAFLD and to develop strategies to improve awareness and risk stratification for this important liver disease.