Crohn’s Disease is a Greater Risk Factor for Nonalcoholic Fatty Liver Disease Compared to Ulcerative Colitis: A Systematic Review

Crohn's disease (CD) and ulcerative colitis (UC) are inflammatory bowel diseases that have been associated with nonalcoholic fatty liver disease (NAFLD). This systematic review aimed to examine whether Crohn's disease confers a greater risk for nonalcoholic fatty liver disease compared to ulcerative colitis. A comprehensive search of electronic databases from January 2000 to May 2023 was conducted to identify observational studies investigating the association between Crohn's disease or ulcerative colitis and nonalcoholic fatty liver disease. Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) 2020 checklist ensured transparent reporting, and the Newcastle-Ottawa Scale was used to assess study quality. Data synthesis revealed higher nonalcoholic fatty liver disease prevalence among Crohn's disease patients compared to ulcerative colitis patients across regions. Ten studies published between 2016 and 2022, encompassing a total of 4164 participants from three continents, were included in the review. The median proportion of Crohn's disease patients with nonalcoholic fatty liver disease was 37.22% (range: 10.95-53.80%), while it was 27.55% (range: 8.60-46.20%) for ulcerative colitis patients. Subgroup analysis by region confirmed CD's higher NAFLD risk. Median proportions for CD patients who developed NAFLD from North America, Europe, and Asia were 25.97% (range: 14.6-37.33%), 47.01% (range: 14.2-53.8%), and 20.78% (range: 10.95-30.6%), respectively, and the median proportion of persons with UC who developed NAFLD in studies from North America, Europe, and Asia were 17.28% (range: 8.6-25.96%), 37.70% (range: 25.64-46.20%), and 19.52% (range: 10.14-28.90%), respectively. Variations suggest differing mechanisms, disease features, and therapeutics. Transmural inflammation in Crohn's disease may increase metabolic abnormalities, including nonalcoholic fatty liver disease. Geographic differences in lifestyle, genetics, and environmental variables may also contribute. This review demonstrates that Crohn's disease patients face a higher nonalcoholic fatty liver disease risk than ulcerative colitis patients, emphasizing the need for early monitoring and prevention. Further studies are warranted to understand mechanisms and develop tailored management approaches.