title: The Domestic/International Gastroenterology Surveillance Study (DIGEST): design, subjects and methods.
abstract: BACKGROUND
  The Domestic/International Gastroenterology Surveillance Study (DIGEST) was designed to examine the 3-month prevalence of upper gastrointestinal (GI) symptoms internationally and the impact of these symptoms on healthcare usage and quality of life.
  
  
  METHODS
  The study sample was derived from the urban, adult (> or = 18 years) population of Canada, Italy, Japan, The Netherlands, Switzerland, the USA and the Nordic countries (Denmark, Finland, Norway and Sweden). Subjects were randomly recruited on a house-to-house basis in all countries except the USA and Italy, where telephone recruitment was carried out. Participants were interviewed in their own homes (house-to-house recruitment) or at a central location (telephone recruitment). The DIGEST questionnaire consisted of two sections. The first was a newly developed questionnaire consisting of 27 questions examining the prevalence, frequency and severity of upper GI symptoms, and their impact on healthcare use and daily activities. It also examined a number of demographic and socioeconomic variables. This part of the questionnaire was evaluated and pilot-tested before commencement of the survey. The second part of the questionnaire consisted of the local language version of the Psychological General Well-Being Index (PGWBI), a validated generic quality-of-life scale. Following completion of the survey, subjects with upper GI symptoms were classified on the basis of their most bothersome symptom into three symptom groups: gastro-oesophageal reflux-like, ulcer-like or dysmotility-like.
  
  
  CONCLUSIONS
  Rigorous design, standardization of interview techniques and prior evaluation of the DIGEST questionnaire, provided a firm foundation for reliable data collection, analysis and interpretation.
authors.affiliation: Janssen Ortho Inc, Toronto, Canada. aeggles1@joica.jnj.com
authors.forename: A
authors.initials: A
authors.lastname: Eggleston
authors.forename: C
authors.initials: C
authors.lastname: Farup
authors.forename: R
authors.initials: R
authors.lastname: Meier
mesh_terms: D000328:Adult; D000368:Aged; D002170:Canada / Q000453:epidemiology; D017281:Cost of Illness; D004415:Dyspepsia / Q000191:economics / Q000453:epidemiology; D015340:Epidemiologic Research Design; D005260:Female; D005387:Finland / Q000453:epidemiology; D005767:Gastrointestinal Diseases / Q000191:economics / Q000453:epidemiology*; D014943:Global Health; D006801:Humans; D007558:Italy / Q000453:epidemiology; D007564:Japan / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D011159:Population Surveillance; D011788:Quality of Life; D012537:Scandinavian and Nordic Countries / Q000453:epidemiology; D013557:Switzerland / Q000453:epidemiology; D014481:United States / Q000453:epidemiology; D014505:Urban Population