Letter: an allergic phenotype in patients with eosinophilic oesophagitis and asthma

Abstract

We read with great interest the study by Harer et al.1 aiming to better define an allergic phenotype in adult patients with asthma and eosinophilic oesophagitis (EoE). Three issues arise. First, the status of the oesophagus in the non-EoE group is not defined. EoE can be subclinical prior to presentation with dysphagia or food bolus obstruction.2 Furthermore, the influence of gastro-oesophageal reflux disease that can be associated with both asthma and eosinophilic infiltration in the oesophagus was not addressed. Secondly, the definition of food allergy applied refers only to ‘Type 1’3 IgE-mediated immediate hypersensitivity conditions (e.g. angioedema/anaphylaxis). Although this type of food allergy can occur in EoE patients, it is considered a separate condition, but this distinction is not made. Food challenge was documented too infrequently to be useful. The definition of food allergy in EoE patients and the need for reliable investigations is of current debate4 especially as, for example, 64% of adult EoE patients demonstrated histological improvement following the use of a six-food elimination diet, although only 13% had positive skin prick tests. Hence, either skin prick testing has limited utility or EoE may represent a disease with a range of immunological mechanisms including ‘atopic’ as well as delayed ‘cell-mediated’ immunity. Thirdly, food allergy as documented was the strongest predictor of EoE, yet it was omitted from the multivariate analysis. The reason for this was not addressed. While the development of a scoring scale/screening tool is to be applauded, its construction from an incomplete data set excluding food allergy based on limited investigations, and a potentially flawed definition of food allergy, is premature, given the evolving understanding of this condition. A prospective data set, with uniform investigation and a standardised definition of food allergy, is hence suggested. Declaration of personal and funding interests: None.