Development of the Northwestern Esophageal Quality of Life Scale: A Hybrid Measure for Use Across Esophageal Conditions.

Objective: Measures of health-related quality of life (HRQOL) in chronic esophageal conditions such as gastroesophageal reflux disease, eosinophilic esophagitis, and achalasia are widely used to measure this important patient-reported outcome. We seek to leverage these existing measures to create a hybrid measure of esophageal illness HRQOL (the Northwestern Esophageal Quality of Life-NEQOL), allowing for broad use across diseases while maintaining sensitivity to nuances of a specific condition.

Methods: A three-step, mixed-methods process per FDA guidelines for patient-reported outcome (PRO) development was followed: review and consolidation of existing HRQOL measure items into a single questionnaire, reliability and validity analyses (principle components factor analysis, Cronbach alpha, Guttman split-half, inter-item correlation, test-retest correlation, and Pearson's correlation with related constructs) based on responses from a representative sample of esophageal illness patients, and individual structured cognitive interviews with patients for item refinement and reduction.

Results: An initial 30-item measure was created. Two-hundred twelve patients completed the reliability and validity portion of the study, and 15 completed cognitive interviews. Factor analysis and item-reduction resulted in 11 items being removed from the NEQOL prior to patient interviews. Construct validity was supported by moderate and significant correlations with psychological distress and general HRQOL. Test-retest reliability was excellent. Following patient interviews, an additional 5 items were removed because of floor effects or participant feedback yielding a 14-item, single scale measure of HRQOL.

Conclusions: Although more research is warranted, the NEQOL is a reliable and a valid hybrid measure of disease-specific HRQOL across several chronic esophageal conditions.