title: The Reflux Disease Questionnaire: a measure for assessment of treatment response in clinical trials.
abstract: BACKGROUND
  Critical needs for treatment trials in gastroesophageal reflux disease (GERD) include assessing response to treatment, evaluating symptom severity, and translation of symptom questionnaires into multiple languages. We evaluated the previously validated Reflux Disease Questionnaire (RDQ) for internal consistency, reliability, responsiveness to change during treatment and the concordance between RDQ and specialty physician assessment of symptom severity, after translation into Swedish and Norwegian.
  
  
  METHODS
  Performance of the RDQ after translation into Swedish and Norwegian was evaluated in 439 patients with presumed GERD in a randomized, double-blind trial of active treatment with a proton pump inhibitor.
  
  
  RESULTS
  The responsiveness was excellent across three RDQ indicators. Mean change scores in patients on active treatment were large, also reflected in effect sizes that ranged from a low of 1.05 (dyspepsia) to a high of 2.05 (heartburn) and standardized response means 0.99 (dyspepsia) and 1.52 (heartburn). A good positive correlation between physician severity ratings and RDQ scale scores was seen. The internal consistency reliability using alpha coefficients of the scales, regardless of language, ranged from 0.67 to 0.89.
  
  
  CONCLUSIONS
  The results provide strong evidence that the RDQ is amenable to translation and represents a viable instrument for assessing response to treatment, and symptom severity.
authors.affiliation: Park Nicollet Clinic and University of Minnesota Medical School, Minneapolis, MN 55416-2699, USA. shawmj@parknicollet.com
authors.forename: Michael
authors.initials: M
authors.lastname: Shaw
authors.forename: John
authors.initials: J
authors.lastname: Dent
authors.forename: Timothy
authors.initials: T
authors.lastname: Beebe
authors.forename: Ola
authors.initials: O
authors.lastname: Junghard
authors.forename: Ingela
authors.initials: I
authors.lastname: Wiklund
authors.forename: Tore
authors.initials: T
authors.lastname: Lind
authors.forename: Folke
authors.initials: F
authors.lastname: Johnsson
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D005260:Female; D005764:Gastroesophageal Reflux / Q000175:diagnosis* / Q000523:psychology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011594:Psychometrics; D011788:Quality of Life; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires