Idiopathic acute pancreatitis in patients with inflammatory bowel disease: a multicentric cohort study

Abstract Background Idiopathic acute pancreatitis (IAP) in patients with inflammatory bowel disease (IBD) is not well characterized. Our purpose was to better understand this condition and its natural history. Methods Retrospective cohort study conducted at nine Spanish IBD referral centers. Patients with IBD and a first episode of acute pancreatitis (AP) between 1998-2018 were included. Patients with a previous episode of AP or a diagnosis of chronic pancreatitis were excluded. IAP and non-IAP were compared by multivariate logistic regression and survival analysis. Results We identified 185 patients with IBD (68.7% Crohn´s disease) and a first episode of AP. Thirty-eight of those 185 (20.6%) fulfilled criteria for IAP. There were no severe cases of IAP. On multivariate analysis, AP before IBD diagnosis (21.1% vs. 3.4%, p=0.04) and ulcerative colitis (52.6% vs. 23.1%, p=0.002) were significantly more common in IAP. Further work-up was performed in 16/38 (42%) IAP patients, and a cause was identified in 6/16 (37.5%). Median time from AP to the end of follow-up was 6.3 years (3.1-10). Five-year risk of AP recurrence was significantly higher in IAP group (28% vs. 5.1%, log-rank p=0.001), with a median time to first recurrence of 4.4 months (2.9-12.2). Conclusions IAP represents the second cause of AP in patients with IBD. It is more frequent in ulcerative colitis, and presents a high risk of recurrence. Additional imaging work-up after a first episode of IAP in IBD patients is highly advisable, as it identifies a cause in more than one-third of cases.