Background/Aims: Proteinase 3 antineutrophil cytoplasmic antibody (PR3-ANCA) is a serologic marker for granulomatosis with polyangiitis. However, recent studies have also shown their role as diagnostic markers for ulcerative colitis (UC). This study was performed to investigate the clinical roles of PR3-ANCAs in the disease severity, disease extension, and clinical course of UC. Methods: Serum PR3-ANCAs were measured in 173 UC patients including 77 patients with new-onset patients UC diagnosed within 1 month, 110 patients with Crohn’s disease, 48 patients with other intestinal diseases, and 71 healthy controls. Associations between the PR3-ANCA titer and clinical data, such as disease severity, disease extension, and clinical course, were assessed. The clinical utility of PR3-ANCA measurement was evaluated by receiver operating characteristic (ROC) analysis. Results: PR3-ANCA ≥3.5 U/mL demonstrated 44.5% sensitivity and 95.6% specificity for thediagnosis of UC in all patients. PR3-ANCA positivity was more prevalent in the 77 new-onset UC patients (58.4%). In this group, the disease severity and extension were more severe in PR3-ANCA positive patients than in PR3-ANCA negative group (p<0.001). After treatment, the partial Mayo scores were significantly decreased with the PR3-ANCA titers. The proportion of patients who required steroids for induction therapy was significantly higher among PR3-ANCA positive than negative group. ROC analysis revealed that PR3-ANCA ≥3.5 U/mL had 75% sensitivity and 69.0% specificity for steroid requirement in new-onset UC patients. Conclusions Our results indicate that PR3-ANCA measurement is useful not only for diagnosing UC but also for evaluating disease severity and extension and predicting the clinical course.

Background/Aims: The frequency and details of nonalcoholic fatty liver disease (NAFLD) complications in patients with inflammatory bowel disease (IBD) remain unclear. This study aimed to clarify characteristics of NAFLD in patients with IBD. Methods: We retrospectively identified and enrolled patients with IBD diagnosed with or without NAFLD by undergoing abdominal computed tomography (CT) at our institution between 2005 and 2020. The primary endpoint was the complication rate of NAFLD in patients with IBD. Secondary endpoints were the clinical characteristics of nonobese patients with IBD and comorbid NAFLD and their association with nutritional and inflammatory parameters. Results: Twenty-one (21.9%) of 96 eligible patients with IBD also had NAFLD. In nonobese patients (defined as patients with a body mass index <25 kg/m2), C-reactive protein (CRP; P<0.001) and alanine aminotransferase (P=0.018) levels were higher and the albumin level (P=0.005) and prognostic nutritional index (PNI; P=0.002) values were lower in patients with NAFLD than in those without NAFLD. The PNI value was positively correlated (P<0.001) and the CRP level was negatively correlated (P=0.001) with the hepatosplenic ratio. However, in the NAFLD combined group, PNI (P<0.05) and CRP values (P<0.001) were improved over time after CT imaging by continuing IBD treatment. Conclusions Worsening nutritional and inflammatory status in IBD patients is associated with complications of NAFLD. Diagnosis of NAFLD in IBD patients using CT imaging might be useful not only for early detection of NAFLD but also in assessing the need for therapeutic intervention for IBD.