BACKGROUND Nonalcoholic fatty liver disease (NAFLD) is common in the German population, with an even higher prevalence in inflammatory bowel disease patients. AIM To investigate the risk factors for NAFLD in inflammatory bowel disease patients. METHODS This monocentric retrospective study with a cross-sectional and a longitudinal part included 694 patients. Inclusion criteria were diagnosed inflammatory bowel disease, age ≥ 18 years, availability of at least one abdominal ultrasound. Patients with infectious or suspected alcoholic fatty liver disease were excluded. NAFLD was defined by increased echogenicity at liver ultrasound. Demographic characteristics, disease activity and medications were analyzed as potential risk factors. Parameters influencing the course of NAFLD were identified by a generalized linear mixed model. RESULTS Forty-eight percent of Crohn’s disease (CD) patients and 44% of ulcerative colitis patients suffered from NAFLD. Its occurrence was associated with greater age, hypertension and body mass index (BMI) in both groups, and with higher disease activity and dyslipidemia in CD. 2467 ultrasound results were included in the longitudinal analysis. Risk factors for NAFLD were age, BMI, higher disease activity, bowel resection(s), endoscopic activity and azathioprine use in CD; and BMI and endoscopic activity in ulcerative colitis. CONCLUSION NAFLD was highly prevalent in this cohort of German inflammatory bowel disease patients. Its risk increased mainly with rising age and BMI. This analysis provides a rationale for non-invasive liver screening in inflammatory bowel disease patients.

Background Non-alcohol fatty liver disease (NAFLD) is a widespread disease in Europe with a prevalence of 20–30% in the German population. Some studies have revealed even higher prevalence in patients with inflammatory bowel diseases (IBD). The majority of prior studies on this subject are cross-sectional analyses. Longitudinal data for the identification of prognostic parameters are missing. Methods This is a monocentric retrospective study encompassing both a cross-sectional and a longitudinal part. The study included 440 patients with Crohn’s disease (CD) and 254 patients with ulcerative colitis (UC). Inclusion criteria were diagnosis of IBD, age >17 years, and having received at least one abdominal ultrasound of the liver at the IBD outpatient clinic of the Heidelberg University Hospital. Exclusion criteria were presence of any infectious liver disease, alcoholic fatty liver disease, or documented abuse of alcohol. NAFLD was defined by echogenicity via ultrasoud and assigned in degrees of severity (no, mild, moderate or severe steatosis). As potential risk factors for the development of NAFLD, demographic characteristics, IBD activity (clinical scores, laboratory results, endoscopic or ultrasound findings), and IBD medications were investigated. Results The prevalence of NAFLD was 48% in CD patients and 44% in UC patients. Higher age and body mass index (BMI) were significantly associated with the occurrence of NAFLD. NAFLD was associated with higher Harvey Bradshaw Index in CD patients, while laboratory results, endoscopic or ultrasound findings proving inflammation were not associated with NAFLD. In UC patients, there was no association between disease activity and NAFLD. The use of steroids, immunomodulators or biologics was not associated with NAFLD, while the use of sulfasalazine was associated with NAFLD only in CD patients. In the longitudinal part of this study, 2467 hepatic ultrasound results were included. Age and BMI in CD patients and BMI in UC patients were significant risk factors in the mixed logistic regression model. Also, in CD patients, higher HBI, former bowel resections, endoscopic disease activity and use of azathioprine–not of steroids–were risk factors of NAFLD. In UC patients, endoscopic disease activity was significantly associated with NAFLD in the mixed logistic regression model. Conclusion There is a high prevalence of NAFLD in German IBD patients. The risk to develop NAFLD increases in older patients and patients with higher BMI. Disease activity and azathioprine use in CD may increase the prevalence of NAFLD. Our study provides a rationale for regular ultrasound screening of the liver in IBD patients.