Autoimmune pancreatitis (AIP) is an immune-mediated disease of the pancreas with distinct
pathophysiology and manifestations. Our aims were to characterize type 1 AIP in a
large pan-European cohort and study the effectiveness of current treatment regimens.We
retrospectively analyzed adults diagnosed since 2005 with type 1 or not-otherwise-specified
AIP in 42 European university hospitals. Type 1 AIP was uniformly diagnosed using
specific diagnostic criteria. Patients with type 2 AIP and those who had undergone
pancreatic surgery were excluded. The primary endpoint was complete remission, defined
as the absence of clinical symptoms and resolution of the index radiological pancreatic
abnormalities attributed to AIP.We included 735 individuals with AIP (69% male; median
age 57 years; 85% White). Steroid treatment was started in 634 patients, of whom 9
(1%) were lost to follow-up. The remaining 625 had a 79% (496/625) complete, 18% (111/625)
partial, and 97% (607/625) cumulative remission rate, while 3% (18/625) did not achieve
remission. No treatment was given in 95 patients, who had a 61% complete (58/95),
19% partial (18/95), and 80% cumulative (76/95) spontaneous remission rate. Higher
(≥0.4 mg/kg/day) corticosteroid doses were no more effective than lower (<0.4 mg/kg/day)
doses (OR 0.428; 95%CI 0.054-3.387) and neither was a starting dose duration > 2 weeks
(OR 0.908; 95%CI 0.818-1.009). Elevated IgG4 levels were independently associated
with a decreased chance of complete remission (OR 0.639; 95%CI 0.427-0.955). Relapse
occurred in 30% of patients. Relapses within 6 months of remission induction were
independent of the steroid tapering duration, induction treatment duration, and total
cumulative dose.Patients with type 1 AIP and elevated IgG4 level may need closer monitoring.
For remission induction, a starting dose of 0.4 mg/kg/day for 2 weeks followed by
a short taper period seems effective. This study provides no evidence to support more
aggressive regimens.
