Objective: To establish appropriate steroid therapy regimen for autoimmune pancreatitis (AIP).
Design, setting and participants: Retrospective survey of AIP treatment was conducted in 17 centers in Japan.
Interventions: Steroid therapy.
Main outcome measures: Rate of remission and relapse.
Results: Of 563 AIP patients, 459 (82%) received steroid therapy. Remission rate of steroid-treated AIP was 98%, which was significantly higher than that of patients without steroid therapy (74%, 77/104; p<0.001). Steroid therapy was given for obstructive jaundice (60%), abdominal pain (11%), associated extrapancreatic lesions except the biliary duct (11%), and diffuse enlargement of the pancreas (10%). There was no relationship between the period necessary to achieve remission and the initial dose (30 mg/day vs. 40 mg/day) of prednisolone. Maintenance steroid therapy was performed in 377 (82%) of 459 steroid-treated patients, and steroid therapy was stopped in 104 patients. The relapse rate of AIP patients on maintenance therapy was 23% (63/273), which was significantly lower than that of patients who stopped maintenance therapy (34%, 35/104; p=0.048). From the start of steroid therapy, 56% (55/99) relapsed within 1 year, and 92% (91/99) relapsed within 3 years. Of the 89 relapsed patients, 83 (93%) received steroid re-treatment, and steroid re-treatment was effective in 97% of them.
Conclusions: The major indication for steroid therapy in AIP is the presence of symptoms. We recommend an initial prednisolone dose of 0.6 mg/kg/day, which is then reduced to a maintenance dose over a period of 3-6 months. Maintenance therapy with low-dose steroid reduces but dose not eliminate relapses.