Correlation Between Long-term Outcome and Steroid Therapy in Type 1 Autoimmune Pancreatitis: Relapse, Malignancy and Side Effect of Steroid

Objectives: Autoimmune pancreatitis (AIP) responds well to corticosteroid therapy (CST), and CST is essential to induce remission. However, the correlation between long-term outcome and CST has not been evaluated. We aimed to clarify the correlation between long-term outcome of AIP and CST.

Material And Methods: We retrospectively evaluated relapse, risk of malignancy and side effects of CST by focusing on the correlation with CST in 84 patients with type 1 AIP.

Results: The incidence of relapse was 23.8%. The frequency of relapse after CST administration was significantly lower in patients taking CST for >6 months than in those who did not (22% versus 67%; p = 0.036). The incidence of malignancy was 10.7%. The standardized incidence ratio of malignancy was 2.14 [95% confidence interval 0.74-3.54]. There were no significant correlations between development of malignancy and CST. The incidences of total and serious side effects due to CST were 75% and 19.1%, respectively. Relapse was the only significant independent predictive risk factor for serious side effects in a multivariate analysis (odds ratio 4.065; 95% confidence interval 1.125-14.706; p = 0.032). The cumulative dose of corticosteroid was significantly higher in patients with serious side effects than in those without (12,645 mg versus 7322 mg; p = 0.041).

Conclusions: CST reduces relapse of AIP. However, CST causes serious side effects, particularly in relapsing patients. Alternative maintenance therapy to prevent relapse is needed.