Pancreatic manifestations in rheumatoid arthritis: a national population-based study

Objectives. RA is a systemic autoimmune disease characterized by persistent joint inflammation. Extra-articular manifestations of RA can involve different organs including the gastrointestinal (GI) system. Using a large database, we sought to describe the epidemiology of pancreas involvement in RA. Methods. We queried a multicentre database (Explorys Inc, Cleveland, OH, USA), an aggregate of electronic health record data from 26 major integrated US healthcare systems in the US from 1999 to 2019. After excluding patients younger than 18, a cohort of individuals with Systematized Nomenclature of Medicine - Clinical Terms (SNOMED-CT) diagnosis of RA was identified. Within this cohort, patients who developed a SNOMED-CT diagnosis of acute pancreatitis (AP), chronic pancreatitis (CP) and primary pancreatic cancer (PaCa) after at least 30 days of RA diagnosis were identified. Statistical analysis for multivariate model was performed using Statistical Package for Social Sciences (SPSS version 25, IBM Corp) to adjust for several factors. Results. Of the 56 183 720 individuals in the database, 518 280 patients had a diagnosis of RA (0.92%). Using a multivariate regression model, patients with RA were more likely to develop AP [odds ratio (OR): 2.51; 95% CI: 2.41, 2.60], CP (OR: 2.97; 95% CI: 2.70, 3.26) and PaC (OR: 1.79; 95% CI: 1.52, 2.10). Conclusion. In this large database, we found a modest increased risk of AP and CP among patients with RA after adjusting for the common causes of pancreatitis. Further studies are required to better understand this association and the effect of medications used for RA.