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.

Background & aims

Previous studies have shown a potential association between nonalcoholic fatty liver disease (NAFLD) and some immune-mediated inflammatory diseases, such as rheumatoid arthritis (RA), but this association has not been analyzed systematically. Therefore, we aimed to perform a systematic review and meta-analysis to ascertain a pooled prevalence estimate of NAFLD among patients with RA to fill this gap in knowledge.

Methods

We conducted a literature search in PubMed, Embase, Web of Science, Scopus, and ProQuest, for observational studies published from inception to August 31, 2022, which reported prevalence of NAFLD in 100 or more adult (age, ≥18 y) patients with RA. To be included, NAFLD diagnosis was based on either imaging or histologic assessment. The results were presented as pooled prevalence, odds ratio, and 95% CI. The I² statistic was used to measure the heterogeneity between studies.

Results

This systematic review included 9 eligible studies derived from 4 continents comprising 2178 patients (78.8% women) with RA. The pooled prevalence of NAFLD was 35.3% (95% CI, 19.9-50.6; I² = 98.6%; P < .001) in patients with RA. All studies used ultrasound for the diagnosis of NAFLD, except for 1 study that used transient elastography. The pooled prevalence of NAFLD in men with RA was significantly higher than in women with RA (35.2%; 95% CI, 24.0-46.5 compared with 22.2%; 95% CI, 17.9-26.58; P for interaction = .048). Each 1-unit increase in body mass index was associated directly with a 24% increased risk of NAFLD in RA patients (adjusted odds ratio, 1.24; 95% CI, 1.17-1.31; I² = 0.0%; P = .518).

Conclusions

Based on this meta-analysis, 1 in 3 patients with RA had NAFLD, which appears comparable with its overall prevalence among the general population. Clinicians should actively screen for NAFLD in patients with RA.