The effect of steroid therapy on pancreatic exocrine function in Autoimmune Pancreatitis

Background/Objectives Autoimmune pancreatitis (AIP) is a steroid-responsive inflammatory disease of the pancreas. Few studies investigated pancreatic exocrine function (PEF) in patients suffering from AIP and no definitive data are available on the effect of steroids in PEF recovery. Aim of the study is the evaluation of severe pancreatic insufficiency (sPEI) prevalence in AIP at clinical onset and after steroid treatment. Methods 312 Patients with diagnosis of AIP between January 1st 2010 and December 31st 2020 were identified in our prospectively maintained register. Patients with a pre-steroid treatment dosage of fecal elastase-1 (FE-1) were included. Changes in PEF were evaluated in patients with available pre- and post-treatment FE (between 3 and 12 months after steroid). Results One-hundred-twenty-four patients were included, with a median FE-1 of 122 (Q1-Q3: 15-379) μg/g at baseline. Fifty-nine (47.6%) had sPEI (FE-1<100 μg/g). Univariable analysis identified type 1 AIP, radiological involvement of the head of the pancreas (diffuse involvement of the pancreas or focal involvement of the head), weight loss, age and diabetes as associated with a greater risk of sPEI. However, at multivariable analysis, only the involvement of the head of the pancreas was identified as independent risk factor for sPEI. After steroids, mean FE-1 changed from 64 (15-340) to 202 (40-387) μg/g (P=0.058) and head involvement was the only predictor of improvement of sPEI. Conclusion The inflammatory involvement of the head of the pancreas is associated with PEF severity, as well as PEF improvement after treatment with steroids in patients with AIP.