Acute pancreatitis in inflammatory bowel disease, with special reference to azathioprine-induced pancreatitis

Background Pancreatitis is a potentially severe condition. Patients with inflammatory bowel disease (IBD) seem to be at increased risk for acute pancreatitis. Aim To describe the incidence, main causes and possible predictive factors of acute pancreatitis in inflammatory bowel disease. Methods Information was retrospectively extracted from the clinical records of patients followed in the IBD Units of nine hospitals in Madrid (n = 5073). Results A total of 82 acute pancreatitis episodes were diagnosed (cumulative incidence, 1.6%); 98% of them were mild. Recurrent acute pancreatitis developed in 13% of patients. Most cases of acute pancreatitis (63.4%) were attributed to drug exposure [azathioprine/mercaptopurine (AZA/MP) n = 46, mesalazine (mesalamine) n = 6]; 20.7% were idiopathic, and 12.2% were biliary. Incidence of acute pancreatitis in patients treated with AZA/MP was 3.1%. In patients with acute pancreatitis, female gender (OR 3.4 95% CI: 1.3-9.3; P = 0.012) and Crohn's disease (CD) (OR 5.8 95% CI: 1.6-20.6; P = 0.007) were risk factors for AZA/MP-associated acute pancreatitis, the latter also when analysed only in patients treated with AZA/MP (n = 1477) (OR 5.2 95% CI: 1.8-14; P = 0.002). Conclusions The incidence of acute pancreatitis in our IBD patients (1.6%) is similar to that previously described. Drugs, mainly AZA/MP, are the leading cause. AZA-induced acute pancreatitis is always mild. Patients with CD are at a higher risk for AZA/MP-associated acute pancreatitis. The frequency of idiopathic acute pancreatitis is higher than expected, suggesting that part of these cases could be extraintestinal manifestations of IBD.