Increased incidence of azathioprine-induced pancreatitis in Crohn's disease compared with other diseases

Background: Azathioprine is widely used in Crohn's disease. A major drawback is the occurrence of side-effects, especially acute pancreatitis. Acute pancreatitis is rarely seen when azathioprine is used for other diseases than Crohn's disease. Aim: To survey side-effects of azathioprine after liver or renal transplantation, for systemic lupus erythematosis, Wegener's granulomatosis, autoimmune hepatitis, rheumatoid arthritis, ulcerative colitis or Crohn's disease. Methods: A computerized search using the term 'azathioprine' or 'imuran' was performed on the Hospital Information System of the university hospital Groningen, resulting in 1564 patients matching our criteria. Results: Eleven of 224 patients with Crohn's disease experienced acute pancreatitis (4.9%) compared with two of 129 (1.5%) with autoimmune hepatitis, two of 388 (0.5%) after renal transplantation, one of 254 (0.4%) after liver transplantation. Acute pancreatitis was more prevalent in Crohn's disease compared with any other disease. Azathioprine-toxicity necessitating withdrawal occurred significantly (P < 0,05) more in rheumatoid arthritis(78 of 317), ulcerative colitis (20 of 94) and Crohn's disease (52 of 224) compared with systemic lupus erythematosis (five of 73), Wegener's granulomatosis (six of 85), autoimmune hepatitis (eight of 129), after liver transplantation (17 of 254) and after renal transplantation (22 of 388). Conclusions: Acute pancreatitis is strongly associated with Crohn's disease and rarely occurs with other underlying conditions. Overall azathioprine-induced toxicity and the necessity of withdrawal is more common in inflammatory bowel disease and rheumatoid arthritis compared with other diseases.