Validation of the novel Eosinophilic Esophagitis Impact Questionnaire

Abstract Background Eosinophilic esophagitis (EoE) has a detrimental effect on health-related quality of life (HRQOL). The Eosinophilic Esophagitis Impact Questionnaire (EoE-IQ) is a novel patient-reported outcome (PRO) measure assessing the impact of EoE on HRQOL. To assess suitability of the EoE-IQ, its measurement properties were evaluated. Methods Using baseline and week 24 data from the pivotal, randomized, placebo-controlled, multinational phase 3 R668-EE-1774 trial (NCT03633617) of dupilumab, we evaluated EoE-IQ’s measurement properties (including reliability, construct and known-groups validity, and ability to detect change) and established the threshold for change in scores that can be considered clinically meaningful. Results The analysis population comprised 239 adults and adolescents with EoE. Mean age was 28.1 (standard deviation, 13.14) years; 63.6% were male, and 90.4% were White. Reliability estimates for the EoE-IQ average score exceeded acceptable thresholds for patients who were stable as indicated by ratings of Patient Global Impression of Severity (PGIS) and Change (PGIC) (intraclass correlation coefficients, 0.75 and 0.81). Construct validity correlations with other EoE-specific PRO scores were moderate at baseline (|r|= 0.44–0.60) and moderate to strong at week 24 (|r|= 0.61–0.72). In known-groups analysis, EoE-IQ average score discriminated among groups of patients at varying EoE severity levels defined by PGIS scores. A ≥ 0.6-point reduction in EoE-IQ average score (where scores range from 1 to 5, with higher scores indicating worse HRQOL) from baseline to week 24 can be considered clinically meaningful. Conclusions The EoE-IQ’s measurement properties are acceptable, making it a valid, reliable measure of the HRQOL impacts of EoE among adults and adolescents. Trial registration: ClinicalTrials.gov, NCT03633617. Registered August 14, 2018, https://clinicaltrials.gov/study/NCT03633617 .