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

Abstract

Objectives: 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.

Conflict of interest statement

Guarantor of the article: Alyse Bedell, BA. Specific author contributions: Tiffany H. Taft, Laurie Keefer, and John Pandolfino planned the study. Alyse Bedell and Tiffany H. Taft conducted the study and prepared the manuscript. Laurie Keefer and John Pandolfino reviewed and contributed to the manuscript. Alyse Bedell, Tiffany H. Taft, Laurie Keefer, and John Pandolfino approved the final draft submitted. Potential competing interests: None.

Figures

Figure 1

Three-step process for PRO development of NEQOL. HRQOL, health-related quality of life; NEQOL, Northwestern Esophageal Quality of Life; PRO, patient-reported outcome; PCFA, Partial Confirmatory Factor Analysis.