Long-term prognosis of autoimmune pancreatitis with and without corticosteroid treatment

Objectives: Autoimmune pancreatitis (AIP) is a unique form of chronic pancreatitis, and has a favourable response to corticosteroid treatment (CST). Little is known, however, about the long-term outcome of AIP. This study aimed to document the prognosis without and with CST, and to examine the indication for CST. Patients and methods: The prognosis and clinical features of 23 patients without CST and 19 patients treated with CST from onset were investigated. In addition, factors concerning the late occurrence of unfavourable events related to AIP were examined. Results: The patients without CST were 19 men and four women, with an average age of 66 years. After an average observation period of 25 months, 16 patients (70%) developed unfavourable events including obstructive jaundice as a result of distal bile duct stenosis in four, growing pseudocyst in one, sclerogenic changes of extrapancreatic bile duct in nine, hydronephrosis as a result of retroperitoneal fibrosis in one, and interstitial nephritis in one. Patients with obstructive jaundice at onset showed a higher cumulative event occurrence rate (p = 0.025). The patients treated with CST were 16 men and three women, with an average age of 64 years. After an average observation period of 23 months, six patients (32%) developed unfavourable events consisting of interstitial pneumonia in three, and a recurrence of obstructive jaundice in three. In multivariate analysis, CST (HR 0.33, 95% CI 0.12-0.89, p = 0.029) and obstructive jaundice at onset (HR 3.09, 95% CI 1.14-8.32, p = 0.026) were significant predictive factors for unfavourable events. Conclusion: CST could reduce AIP-related unfavourable events. The early introduction of CST is recommended especially for patients with obstructive jaundice.