Both inflammation and fibrosis are likely linked with symptom development in individuals with eosinophilic esophagitis (EoE), a chronic, inflammatory immune-mediated illness of the oesophagus. In the context of trials and observational studies of emerging therapies, assessing symptom-based patient-reported outcomes (PROs), defined by the US Food and Drug Administration as “any report of the status of a patient’s health condition that comes directly from the patients, without interpretation of the patient’s response by a clinician or anyone else,” is critical. Lack of symptoms does not indicate the absence of biologic inflammation for the purposes of therapy monitoring; hence, endoscopy with esophageal biopsies should be conducted to evaluate for remaining inflammation. The absence of inflammation does not indicate the absence of symptoms, and subepithelial fibrosis cannot be ruled out. There is presently no published instrument that evaluates the frequency of dysphagia or describes all conceivable methods, techniques, and pain kinds associated with this condition. Only minor reductions in symptom ratings were seen in randomised controlled studies in which symptom response was measured using validated PRO measures.

Accessing the complete range of EoE symptoms and improving PRO measures is a problem that must be overcome in order to properly assess response to present and upcoming medications.