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: 25.6446.20%), 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.
