Supplementary Material for: Histological phenotyping in eosinophilic esophagitis: Localized proximal disease is infrequent, but associated with less severe disease and better disease outcome

Introduction: It is still unknown whether eosinophilic esophagitis (EoE) patients with localized disease are different from those with extended disease.
Methods: We evaluated prospectively included patients in the Swiss EoE cohort. Data on all patients with active disease at baseline, no concomitant gastro-esophageal reflux disease, no strictures at baseline and at least one follow-up visit were analyzed. We compared patients with histologically localized proximal vs distal vs. extended (=proximal and distal) disease with regards to patient, disease characteristics, disease presentation and development of complications.
Results: We included 124 patients with a median of 2.5y of follow-up (73.4% males, median age 35.0y). Ten patients had proximal (8.1%), 46 patients had distal (37.1%), and 68 patients had extended disease (54.8%). Patients with proximal disease were significantly more often females (80%) compared with patients with distal (26.1%, p=0.002) or extended disease (19.1%, p<0.001) and reported less severe symptoms (VAS 0 vs VAS 1, p=0.001). Endoscopic and histological disease was less pronounced in the proximal esophagus of proximal EoE compared to extended disease (EREFS 1.0 vs 3.0, p=0.001; 27.0eos/hpf vs 52.5eos/hpf, p=0.008). Patients with proximal disease were less likely to undergo dilation compared to patients with distal disease in the follow-up (3.3% vs 23.3%, p=0.010). In a multivariate Cox regression model, proximal eosinophilia was less likely to be associated with treatment failure compared to distal eosinophilia.
Discussion/Conclusion: Although isolated proximal EoE is infrequent, it is associated with less severe disease and better disease outcome. Proximal disease appears to present a unique EoE phenotype.