Clinical Profile and Predictors of Repeated Relapse in Type 1 Autoimmune Pancreatitis: A Multicenter Observational Study.

BACKGROUND AND AIM: Type 1 autoimmune pancreatitis (AIP) is a form of pancreatitis that responds well to glucocorticoid therapy and often results in clinical and radiological remission. However, AIP frequently relapses during long-term follow-up. While initial relapse is well described, repeated relapses are poorly understood. This study aimed to clarify their clinical features and predictors.

METHODS

We retrospectively analyzed 270 patients diagnosed with type 1 AIP between 2004 and 2022 across 12 institutions. Clinical characteristics were compared among the non-relapse, single-relapse, and multiple-relapse groups. Predictors of a second relapse were assessed in patients who experienced at least one relapse using Kaplan-Meier and Cox regression analyses.

RESULTS

During a median follow-up of 65 months, 107 patients (40%) experienced at least one relapse, and 32 (12%) had multiple relapses. The median time to second relapse was 49 months, and the cumulative second relapse rate reached 47.4% at 7 years. Multivariable analysis identified extra-pancreatic sclerosing cholangitis at first relapse as an independent predictor of a second relapse (hazard ratio, 2.773; 95% confidence interval, 1.294-5.941; p = 0.009). Furthermore, 61% of patients whose first relapse involved the extra-pancreatic bile duct experienced multiple relapses, often at the same site, and 73% of them were still on glucocorticoid therapy at the second relapse.

CONCLUSIONS

Second and subsequent relapses are common in type 1 AIP, and are particularly likely when the first relapse involves extra-pancreatic sclerosing cholangitis. These patients may require more intensive monitoring and treatment beyond glucocorticoid monotherapy.