Systematic Review of Outcome Measures Used in Observational Studies of Adults with Eosinophilic Esophagitis

Background: Over the last 20 years, diverse outcome measures have been used to evaluate the effectiveness of therapies for eosinophilic esophagitis (EoE). This systematic review aims to identify the readouts used in observational studies of topical corticosteroids, diet, and dilation in adult EoE patients. Methods: We searched MEDLINE and Embase for prospective and retrospective studies (cohorts/case series, randomized open-label, and case-control) evaluating the use of diets, dilation, and topical corticosteroids in adults with EoE. Two authors independently assessed the articles and extracted information about histologic, endoscopic, and patient-reported outcomes and tools used to assess treatment effects. Results: We included 69 studies that met inclusion criteria. EoE-associated endoscopic findings (assessed either as absence/presence or using Endoscopic Reference Score) were evaluated in 24/35, 11/17, and 9/17 studies of topical corticosteroids, diet, and dilation, respectively. Esophageal eosinophil density was recorded in 32/35, 17/17, and 11/17 studies of topical corticosteroids, diet, and dilation, respectively. Patient-reported outcomes were not uniformly used (only in 14, 8, and 3 studies of topical corticosteroids, diet, and dilation, respectively), and most tools were not validated for use in adults with EoE. Conclusions: Despite the lack of an agreed set of core outcomes that should be recorded and reported in studies in adult EoE patients, endoscopic EoE-associated findings and esophageal eosinophil density are commonly used to assess disease activity in observational studies. Standardization of outcomes and data supporting the use of outcomes are needed to facilitate interpretation of evidence, its synthesis, and comparisons of interventions in meta-analyses of therapeutic trials in adults with EoE.