Inflammatory bowel diseases and eosinophilic oesophagitis: Two overlapping disorders?

Abstract

Inflammatory bowel diseases and eosinophilic oesophagitis: Two overlapping disorders?Inflammatory bowel diseases (IBD) and eosinophilic oesophagitis (EoE) are immune-mediated disorders of the gastrointestinal (GI) tract with an increasing incidence worldwide. 1,2 Both diseases are characterised by a loss of tolerance towards luminal antigens favoured by microbiota disruption suggesting that they may share similar pathophysiology. 3,4 Associations between the two diseases have been suggested in previous studies, especially the risk of developing EoE in individuals with IBD. 5 However, data regarding the risk of developing IBD in individuals with EoE are scarce.In the current issue of the United European Gastroenterology Journal, Uchida et al. assessed the risk of developing IBD in individuals with histopathologic-proven diagnosis of EoE. 6 Between 1990 and 2017, using a Swedish nationwide histopathologic database, the authors identified 1587 individuals with EoE. Each of them was matched to five general population reference individuals according to age, sex, and year of diagnosis of EoE, with a total of 7808 individuals. Individuals with EoE were excluded if they had a prior diagnosis of IBD and the follow-up ended in December 2019. Of note, individuals with EoE underwent more endoscopies during follow-up than the reference individuals. Overall, 16 EoE individuals(0.01%) and 21 reference individuals (0.003%), were diagnosed with IBD during follow-up. The risk of developing IBD was 3.5-fold higher in the EoE group compared to matched individuals from the general population. In subgroup analyses, individuals with EoE were at higher risk of developing later Crohn's disease (CD), but not ulcerative colitis (UC). These results suggest that only CD could be associated with EoE. Additionally, the risk of being diagnosed with EoE was 15 times higher in patients with IBD compared to the general population, suggesting a bidirectional association. Some limitations need to be acknowledged. First, surveillance bias could occur as individuals with EoE were more likely to have upper GI endoscopies during follow-up that could identify lesions related to CD. Patients with EoE are more prone to being followed by GI doctors and so undergo subsequent GI endoscopies. Second, important confounding factors are not collected in the Swedish administrative healthcare databases, notably smoking or medications such as proton pump inhibitors, and residual confounding cannot be excluded.