Eosinophilic esophagitis (EoE) is a chronic esophageal inflammatory condition with a prevalence that continues to increase
]. Food allergies are a common cause of EoE, and therefore food restriction is a common treatment
]. Although patients experience significant disease- and treatment-related sequelae, there is no validated EoE-specific health-related quality of life (HRQOL) instrument to document the impact of EoE on the daily lives of affected pediatric patients. Additionally, current clinical practice in EoE pays little attention to patient HRQOL, instead focusing primarily on histologic and symptomatic improvement outcomes
In order to partly address this significant gap in the empirical literature, we recently utilized the Pediatric Quality of Life Inventory™ (PedsQL™) 4.0 Generic Core Scales to investigate the generic HRQOL of patients with eosinophilic gastrointestinal (GI) disease (EGID, including EoE) in comparison with several other pediatric chronic conditions and healthy controls
]. Not only did patients with EGID and their parents report significantly lower generic HRQOL than healthy controls, but they reported generic HRQOL lower than pediatric patients with inflammatory bowel disease, epilepsy, type 1 diabetes, sickle cell disease, post-renal transplantation, cystic fibrosis, and obesity
Although the PedsQL™ 4.0 Generic Core Scales assess generic issues common across healthy and ill pediatric populations
], a disease-specific HRQOL instrument is essential to understanding the particular health issues most germane to pediatric EoE patients from their perspective. In addition, an EoE disease-specific HRQOL instrument would be expected to be more sensitive to detecting change in health status over time within a population of EoE children than a generic scale. To better understand differences in health status within the population of pediatric EoE patients and to enhance the ability to measure the impact of disease-modifying therapies, we previously conducted individual focus interviews of pediatric patients with EoE and parents and solicited medical expert review in the development of the conceptual model and the initial items for a new multidimensional disease-specific HRQOL instrument targeted to pediatric EoE
]. In the current study, we further utilize qualitative methods, specifically cognitive interviewing techniques, to support content validity and to finalize the items for a quantitative analysis subsequent to field testing.
The FDA patient-reported outcome (PRO) guidance for industry defines content validity as evidence demonstrating that an instrument measures “the concept of interest, including evidence that the items and domains of an instrument are appropriate and comprehensive relative to its intended measurement concept, population, and use”
]. Furthermore, the FDA has emphasized the critical value of patient input in supporting content validity, noting that “documentation of patient input in item generation as well as evaluation of patient understanding through cognitive interviewing can contribute to evidence of content validity”
]. Qualitative methods, in particular focus groups/individual interviews and cognitive interviewing techniques, have emerged as the standard methodology for supporting the content validity for new or existing PRO instruments
] and have served as the foundation for previous PedsQL™ Disease-Specific Modules
]. These qualitative methods are consistent with recent FDA guidelines on PRO measures, and as such help establish the content validity of newly developed disease-specific HRQOL items
]. These iterative steps include: a comprehensive review of the literature, expert opinion, and the patient perspective derived from focus groups/individual interviews (used to develop the conceptual model for relevant disease-specific domains), item generation guided by the conceptual model, and the iterative process of revising the items and item content based on patient cognitive interviewing techniques
]. Previously, Flood and colleagues contributed significantly to EoE PRO development by utilizing expert opinion and cognitive interviews to generate a pediatric EoE symptom metric (the Symptom Questionnaire for Eosinophilic Esophagitis) for use by patients aged 8 – 17 and caregivers of patients aged 2 – 7
]. However, this measure was limited by age range and methods of item generation.
Given the lack of an empirically-validated multidimensional pediatric EoE disease-specific HRQOL instrument in the extant literature for patient self-report for ages 5–18
years and parent proxy-report for ages 2–18
years, the objective of the present study was to address this gap in the empirical literature and to describe the qualitative methods, specifically cognitive interviewing techniques, utilized in the further item development and content validation phase for generating the final items for the new PedsQL™ Eosinophilic Esophagitis Module for pediatric patients with EoE.