title: Validation of the reflux symptom questionnaire electronic diary in partial responders to proton pump inhibitor therapy.
abstract: OBJECTIVE
  We aimed to develop and validate the Reflux Symptom Questionnaire electronic Diary (RESQ-eD) for use in clinical trials in patients with a partial response to proton pump inhibitor (PPI) therapy, using methods that meet US Food & Drug Administration (FDA) regulatory standards.
  
  
  METHODS
  Patient interviews were performed to elicit new items and evaluate existing items from the Reflux Disease Questionnaire. The instrument's measurement properties were evaluated, based on data from two clinical trials of patients with gastroesophageal reflux disease (GERD) with a partial response to PPIs who received lesogaberan or placebo as an add-on to PPI therapy.
  
  
  RESULTS
  The content validity phase resulted in 13 RESQ-eD items. Principal component analysis supported a four-domain structure. All domains had a high inter-item correlation (Cronbach's alpha lower 95% confidence limit: 0.87-0.95). Test-retest reliability was good to excellent (intraclass correlation coefficient: 0.65-0.85). Convergent and discriminant validity was confirmed by correlation assessments referencing the Gastrointestinal Symptom Rating Scale. The RESQ-eD demonstrated a good ability to capture change in mean intensity and proportion of symptom-free days. Confirmatory psychometric evaluation verified internal consistency reliability, test-retest reliability, and ability to capture change.
  
  
  CONCLUSIONS
  The RESQ-eD demonstrated good content validity and psychometric properties in the clinical trial setting in patients with GERD who have a partial response to PPI therapy. To our knowledge, the RESQ-eD is the first electronic symptom diary for use in partial responders to PPI that has been developed in line with the FDA guidance on patient-reported outcomes.
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
authors.forename: Nimish
authors.initials: N
authors.lastname: Vakil
authors.forename: Karin
authors.initials: K
authors.lastname: Björck
authors.forename: Hans
authors.initials: H
authors.lastname: Denison
authors.forename: Katarina
authors.initials: K
authors.lastname: Halling
authors.forename: Maria
authors.initials: M
authors.lastname: Karlsson
authors.forename: Jean
authors.initials: J
authors.lastname: Paty
authors.forename: Debra G
authors.initials: DG
authors.lastname: Silberg
authors.forename: Anna
authors.initials: A
authors.lastname: Rydén