Crohn Disease Associated with Increased Risk of NAFLD Compared to Ulcerative Colitis

Athri Kodali, MBBS

Credit: LinkedIn

A systematic review of observational studies investigating the association inflammatory bowel disease and nonalcoholic fatty liver disease (NAFLD) is highlighting a heightened risk of NAFLD among patients with Crohn disease (CD).

Results of the systematic review, which assessed risk for NAFLD among patients with CD and ulcerative colitis (UC), suggest the magnitude of this risk varied across geographic locations.¹

“​​Understanding the differences in the effects of CD and UC on NAFLD risk is critical for doctors, researchers, and policymakers. Early detection, risk stratification, and targeted therapies can all benefit from an accurate assessment of NAFLD prevalence in CD and UC patients,” wrote investigators.¹ “Furthermore, evaluating potential differences in NAFLD risk between CD and UC across geographic locations can provide valuable insights into the impact of genetic, environmental, and cultural factors on disease outcomes.”

Although CD and UC are similar, they involve different areas of the gastrointestinal tract and can differ in symptoms, treatment options, and disease complications.² IBD-related inflammation can cause damage to the intestines and may affect areas outside of the intestines, including the liver.³

To assess the prevalence of NAFLD in patients with CD and UC and compare the risk between the two conditions, a team of investigators led by Athri Kodali, MBBS, of the California Institute of Behavioral Neurosciences and Psychology, qualitatively synthesized studies evaluating the association between UC or CD and NAFLD. Articles were gathered from MEDLINE/PubMed, PubMed Central, and Google Scholar by searching “inflammatory bowel disease,” “Crohn's disease,” “colitis, ulcerative,” “nonalcoholic fatty liver disease,” and “epidemiology” in different combinations.¹

To be included in the analysis, studies were required to evaluate the prevalence of NAFLD in patients with CD and UC, provide sufficient data for analysis, and be published in English. Studies focusing on pediatric populations, case reports, reviews, and editorials were excluded. Investigators identified 18,949 articles in the initial literature search and screened 18,286 after removing duplicates. Of these studies, 124 were selected for further assessment by investigators. In total, 10 studies published between 2016 and 2022 encompassing a total of 4164 participants from three continents met inclusion criteria and were deemed eligible for data analysis.¹

Investigators collected information about authors, year of publication, study design, study duration, country, region, sample size, diagnostic method for NAFLD, and prevalence rates of NAFLD in patients with CD and UC for each of the selected studies. The extracted data were synthesized qualitatively to provide a descriptive overview of the prevalence of NAFLD in CD and UC patients across different studies and regions.¹

Upon analysis, the median proportion of patients with CD with NAFLD was 37.22% (interquartile range [IQR], 10.95-53.80%), while it was 27.55% (IQR, 8.60-46.20%) for patients with UC. In the 2 studies from North America, patients with CD demonstrated a median proportion of NAFLD at 25.97% (IQR, 14.60-37.33%), whereas patients with UC showed a lower median proportion of 17.28% (IQR, 8.60-25.96%). In the 6 studies from Europe, patients with CD had a median proportion of NAFLD at 47.01% (IQR, 14.20-53.8%), while patients with UC had a slightly lower median proportion of 37.70% (IQR, 25.64-46.20%).¹

In the 2 studies from Asia, the prevalence of NAFLD in both patients with CD and patients with UC was lower, with median proportions of 20.78% (IQR, 10.95-30.6%) and 19.52% (IQR, 10.14-28.90%), respectively, suggesting a comparable risk of NAFLD development in this population. With the exception of 1 study in Greece where 26.20% of patients with UC developed NAFLD compared to 14.20% of patients with CD, all other studies found patients with CD were at a higher risk of developing NAFLD. Investigators suggested regional differences may be influenced by genetic, lifestyle, and environmental variables.¹

“The results of this systematic review provide valuable insights into the association between CD and UC with NAFLD. These findings validate the necessity for additional research to understand the underlying mechanisms and explore potential interventions to mitigate the increased risk of NAFLD in CD patients,” concluded investigators.¹

References

1. Kodali A, Okoye C, Klein D, et al. Crohn's Disease is a Greater Risk Factor for Nonalcoholic Fatty Liver Disease Compared to Ulcerative Colitis: A Systematic Review. Cureus. 2023;15(8):e42995. Published 2023 Aug 5. doi:10.7759/cureus.42995

2. Crohn’s & Colitis. What are Crohn’s and Colitis? About Crohn’s and Colitis. Accessed September 11, 2023. https://crohnsandcolitis.ca/About-Crohn-s-Colitis/What-are-Crohns-and-Colitis

3. Johns Hopkins Medicine. Inflammatory Bowel Disease (IBD). Conditions and Diseases. Accessed September 11, 2023. https://www.hopkinsmedicine.org/health/conditions-and-diseases/inflammatory-bowel-disease