Relapse rate and predictors of relapse in a large single center cohort of type 1 autoimmune pancreatitis: long-term follow-up results after steroid therapy with short-duration maintenance treatment.

BACKGROUND

Type 1 autoimmune pancreatitis (AIP), as a pancreatic manifestation of IgG4-related disease, shows a favorable prognosis in the short term. However, disease relapse is common in long-term follow-up, despite a successful initial treatment response. This study aimed to identify the predictors of relapse and long-term outcomes in patients with type 1 AIP.

METHODS

Patients with more than 2 years of follow-up who met the International Consensus Diagnostic Criteria for type 1 AIP were included. Patients who had undergone pancreatic operations associated with AIP or who lacked sufficient clinical data were excluded.

RESULTS

All 138 patients achieved clinical remission with initial steroid therapy, and 66 (47.8%) experienced relapse during a median 60 (range 24-197) months follow-up. Among the relapsed patients, about 74% (49/66) relapsed within 3 years. About 60% (82/138) had other organ involvement (OOI), most commonly in the proximal bile duct (26.8%). At first diagnosis, OOI, and especially OOI of the proximal bile duct, was a significant independent predictor of relapse (hazard ratio 2.65; 95% confidence interval 1.44-4.89; p = 0.002), according to multivariate analysis. During the follow-up period, 16 (11.6%) patients experienced endocrine/exocrine dysfunction and 32 (23.2%) patients developed de novo pancreatic calcifications/stones. No pancreatic cancer occurred in any patients.

CONCLUSIONS

Type 1 AIP has common relapses, and patients with OOI, especially OOI of the proximal bile duct, appear to be at increased risk for relapse. Long-term sequelae, including pancreatic insufficiency and pancreatic calcifications/stones, are common in patients with relapse. To reduce the relapse, longer maintenance treatment may be needed especially for patients at high risk for relapse.