UC San Diego

Background

Non-alcoholic fatty liver disease (NAFLD) is found in inflammatory bowel disease (IBD). However, uncertainties remain on the magnitude of the association.

Aims

To explore systematically the prevalence of, and risk factors for, NAFLD in IBD patients.

Methods

We searched medical literature using Embase, PubMed, Web of Science, Scopus and ProQuest, from inception to September 30, 2021. We included observational studies reporting the prevalence of NAFLD in ≥50 adult patients with IBD. Diagnosis of NAFLD could be based on imaging, histopathology, and/or hepatic steatosis index. Sex, age, body mass index (BMI), diabetes, hypertension, dyslipidemia, prior surgery (bowel resection), corticosteroids, biologics and immunomodulators were assessed as potential risk factors for NAFLD.

Results

Of 1893 citations, 44 eligible studies were finally included, comprising 14 947 subjects from 18 different countries. Pooled prevalence of NAFLD was 30.7% (95% confidence interval [CI] 26.5-34.9) in patients with IBD worldwide, which varied regionally. No significant difference was observed in the odds ratio (OR) of NAFLD among Crohn's disease (CD) patients compared with ulcerative colitis (UC) patients (1.16, 95% CI 0.93-1.44). Risk of NAFLD was almost twice as high in patients with IBD as in healthy subjects (OR 1.96, 95% CI 1.13-3.41). Age (adjusted OR 1.03, 95% CI 1.01-1.05) and BMI (adjusted OR 1.27, 95% CI 1.22-1.32) were statistically significantly associated with increased risk of NAFLD. The pooled prevalence of advanced liver fibrosis in IBD patients with NAFLD was 13.6% (95% CI 7.6-19.7) based on six studies.

Conclusion

Up to one-third of patients with IBD experienced NAFLD worldwide. The risk of NAFLD was two times higher in IBD patients versus healthy subjects.