To assess relationship between Anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis and inflammatory bowel disease (IBD).

This is a retrospective study design. The patients were identified using a preset criteria of patients who have the diagnosis of ANCA associated vasculitis including a diagnosis of granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA) or eosinophilic granulomatosis with polyangiitis (EGPA) with overlapping inflammatory bowel disease (Crohn's disease or ulcerative colitis) in the time period from 01/01/2020 to 08/03/2023. Subsequently data from each patient was collected that will include baseline demographics, disease characteristics, disease activity, treatment information, multiorgan involvement, and pathology findings which were then analyzed.

39 patients were identified that met criteria. 20 patients carried a diagnosis of GPA, 6 had MPA and 4 patients had EGPA. 20 patients with GPA had inflammatory bowel disease, 13 with ulcerative colitis and 6 with Crohn's disease while 1 GPA patient had unspecified inflammatory bowel disease. 4 patients with EGPA had inflammatory bowel disease, 2 with ulcerative colitis and 2 with Crohn's disease. 6 patients with MPA had inflammatory bowel disease, 4 with ulcerative colitis and 2 with Crohn's disease. IBD diagnosis preceded the diagnosis of ANCA vasculitis in 77.8 % of the cases.

Objective observation and deductions from this study raise the concern for a possible pathogenic association of ANCA associated vasculitis and inflammatory bowel disease and more research is needed to identify any causal association or influence of the two systemic disease on each other.