Defining pancreatic damage and symptom burden in IgG4-related autoimmune pancreatitis: A cross-sectional study of 118 patients from a single-center registry.

Objective: Type 1 autoimmune pancreatitis is a common manifestation of IgG4-related disease (IgG4-RD). However, there is a paucity of literature characterizing pancreatic damage and symptom burden in IgG4-RD.

Methods: We performed a cross-sectional analysis of patients who fulfilled the ACR/EULAR IgG4-RD Classification Criteria. Disease features and complications were collected by medical record review. A survey regarding symptoms and disease history was distributed to all patients. Characteristics were compared between patients with and without autoimmune pancreatitis.

Results: Of 303 patients who fulfilled Classification Criteria at the time of the chart review, 118 (39 %) had evidence of autoimmune pancreatitis. Overt indicators of acute pancreatitis (e.g., abdominal pain, nausea/emesis, elevated serum lipase) each occurred in fewer than 50 % of patients with autoimmune pancreatitis. Diabetes mellitus (DM), exocrine pancreatic insufficiency (EPI), or both were present in 47 %, 48 %, and 21 % of the autoimmune pancreatitis patients, respectively. After encouraging all patients to have fecal elastase measured, 40/49 (82 %) stool samples had low elastase concentrations. 9/118 (8 %) had undergone pancreatic resections before the diagnosis was established. 162/325 (50 %) completed surveys (n = 81 [50 %] with autoimmune pancreatitis). Patients with autoimmune pancreatitis reported a higher burden of abdominal pain, weight loss, and changes in stool than those without (all p < 0.05).

Conclusions: Despite an often subclinical presentation, autoimmune pancreatitis is associated with EPI, DM, or both in a high percentage of patients with IgG4-RD. While symptomatic acute pancreatitis may not be common, patient-reported symptom burden due to IgG4-related autoimmune pancreatitis or its complications is greater than previously appreciated.