title: Validation of a 7-point Global Overall Symptom scale to measure the severity of dyspepsia symptoms in clinical trials.
abstract: BACKGROUND
  Currently there is no consensus on the optimal method to measure the severity of dyspepsia symptoms in clinical trials.
  
  
  OBJECTIVE
  To validate the 7-point Global Overall Symptom scale.
  
  
  METHODS
  The Global Overall Symptom scale uses a 7-point Likert scale ranging from 1 = no problem to 7 = a very severe problem. Validation was performed in two randomized-controlled trials (n = 1121 and 512). Construct validity: Global Overall Symptom was compared with the Quality of Life in Reflux And Dyspepsia, Gastrointestinal Symptom Rating Scale, Reflux Disease Questionnaire and 10 specific symptoms using Spearman correlation coefficients. Test-retest reliability: The Intraclass Correlation Coefficient was calculated for patients with stable dyspepsia defined by no change in Overall Treatment Effect score over two visits. Responsiveness: effect size and standardized response mean were also calculated.
  
  
  RESULTS
  Construct validity: Change in Global Overall Symptom score correlated significantly with Quality of Life for Reflux And Dyspepsia, Gastrointestinal Symptom Rating Scale, Reflux Disease Questionnaire and specific symptoms (all P < 0.0002). Reliability: The Intraclass Correlation Coefficient was 0.62 (n = 205) and 0.42 (n = 270). Responsiveness: There was a positive correlation between change in Global Overall Symptom and change in symptom severity. The effect size and standardized response mean were 1.1 and 2.1, respectively.
  
  
  CONCLUSIONS
  The Global Overall Symptom scale is a simple, valid outcome measure for dyspepsia treatment trials.
authors.affiliation: Division of Gastroenterology, Dalhousie University, Halifax, NS, Canada. zanten@dal.ca
authors.forename: S J O
authors.initials: SJ
authors.lastname: Veldhuyzen van Zanten
authors.forename: N
authors.initials: N
authors.lastname: Chiba
authors.forename: D
authors.initials: D
authors.lastname: Armstrong
authors.forename: A N
authors.initials: AN
authors.lastname: Barkun
authors.forename: A B R
authors.initials: AB
authors.lastname: Thomson
authors.forename: V
authors.initials: V
authors.lastname: Mann
authors.forename: S
authors.initials: S
authors.lastname: Escobedo
authors.forename: B
authors.initials: B
authors.lastname: Chakraborty
authors.forename: K
authors.initials: K
authors.lastname: Nevin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000897:Anti-Ulcer Agents / Q000627:therapeutic use; D004415:Dyspepsia / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009853:Omeprazole / Q000627:therapeutic use; D011788:Quality of Life; D016032:Randomized Controlled Trials as Topic; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D016896:Treatment Outcome
chemical_list: D000897:Anti-Ulcer Agents; D009853:Omeprazole