The Worldwide Burden of NAFLD: A Systematic Review and Meta-Analysis of Prevalence and Incidence

Background: Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide and the leading cause of liver-related morbidity and mortality. Although there have been few meta-analyses evaluating the natural history of NAFLD in general population-based studies, only one assessed the global burden of NAFLD. Therefore, we conducted a systematic review and meta-analysis to estimate and examine the temporal trends of worldwide prevalence and incidence of NAFLD. Methods: A search of MEDLINE and EMBASE databases was performed to find reports on the prevalence and incidence of NAFLD until May 25, 2021. We included observational cross-sectional or longitudinal studies performed on samples representative of the general adult population where NAFLD was diagnosed using an imaging method in the absence of excessive alcohol consumption and viral hepatitis. Estimates were created using a random-effects meta-analysis method. Results: We screened 11,444 records and selected 65 papers with a sample population of 1,012,072 for prevalence and 16 papers including a sample size of 381,765 for incidence estimates. The overall worldwide prevalence of NAFLD was 32·6% (95% CI: 30·1, 35·1). The prevalence increased significantly over time ( p <0·01), from 26·4% (95% CI: 20·0, 32·9) for 2005 or before, to 38·0% (95% CI: 31·8, 44·2) for 2016 or later. The overall prevalence of NAFLD in men was significantly higher than in women [40·3% (95% CI: 37·2, 43·5) vs. 25·9% (95% CI: 22·3, 29·5), p<0·001]. The overall NAFLD incidence rate was 47·0 (95% CI: 36·4, 57·6) per 1000 person-years. The incidence rate was 71·0 (95% CI: 48·8, 93·3) in men and 29·6 (95% CI: 20·2, 39·1) in women per 1000 person-years. Conclusion: The worldwide prevalence of NAFLD is significantly higher than previously estimated and is on an alarmingly constant rise. Incidence and prevalence rates are significantly higher among men compared to women.Funding Information: This research was funded by the Canadian Institutes of Health Research project grant (PJT-165848) to Dr. Abdel-Aziz Shaheen.Declaration of Interests: We declare no competing interests.