Abstract
BACKGROUND: The diagnosis of autoimmune pancreatitis (AIP) can be challenging due to nonspecific symptoms, low sensitivity of serologic markers, and some overlap in presentation with pancreatic ductal adenocarcinoma (PDAC). We aimed to quantify delays in the diagnosis of AIP and identify factors associated with diagnostic delay. METHODS: This was a single-center retrospective study between 2013 and 2023 of adult patients diagnosed with type 1 AIP based on HISORt criteria. Patients were compared to a randomly selected group of controls with PDAC. Data on clinical presentation, lab results, imaging, procedures, and initial treatment regimen were collected. Timing to diagnosis and predictive factors were identified and compared between groups. RESULTS: Overall, 41 patients with AIP were identified and compared to 41 patients with PDAC. AIP patients had delays in diagnosis from symptom onset compared to controls (79.1±141.2 vs. 5.2±5.43 weeks, P<0.001). Within the AIP group, female sex (136.6±202.2 vs. 42.3±63.5 weeks, P=0.004) and fatty infiltration of the pancreas on imaging (194.1±163.9 vs. 33.7±60.3 weeks, P<0.001) were associated with delays in diagnosis, respectively. Presenting with jaundice (27.1±33.0 vs. 93.7±156.3 weeks, P=0.01) and obtaining endoscopic ultrasound-guided or surgical biopsies (49.7±79.9 vs. 221.6±262.9 weeks, P=0.04) were associated with a shorter time from symptom onset to diagnosis, respectively. Patients were more promptly diagnosed in the last 5 years of the study compared to the first 5 years (13 vs. 28 weeks, P=0.02). CONCLUSIONS: AIP remains a challenging diagnosis, with extensive delays in diagnosis averaging 1.5 years from symptom onset. Our findings may improve patient identification and reduce diagnostic delay in AIP patients.