title: Gastrointestinal symptoms and subjects cluster into distinct upper and lower groupings in the community: a four nations study.
abstract: OBJECTIVE
  It is unknown whether distinct functional GI (GI) symptom groupings occur in the general population and whether these are similar across different cultures. Although symptom-based diagnostic criteria have been developed for upper and lower GI syndromes (the Rome criteria), the classification is controversial. We aimed to identify whether independent symptom-based subgroups exist in four countries consistent with the Rome criteria.
  
  
  METHODS
  Random samples of the community were mailed a validated questionnaire based on the Bowel Disease Questionnaire in Rochester, MN (n = 2,220), in Sydney, Australia (n = 1,135), and in Essen, Germany (n = 500). A different validated questionnaire was mailed to a random sample in Osthammar, Sweden (n = 1,517). Only the common questions (n = 22) were used in the current analysis, and these were essentially identical in wording. The underlying structure of the item responses was examined using factor analysis. Initial factors were extracted using principal components analysis and then rotated using Varimax. Clustering of symptoms among individuals was examined though cluster analysis, using the factors as the basis for clustering.
  
  
  RESULTS
  Response rates varied from 64% to 80%; responders and nonresponders were similar sociodemographically. All four studies yielded similar factor structures. All countries reported symptom groupings consistent with the irritable bowel syndrome (IBS), dyspepsia and/or gastroesophageal reflux, and constipation; all except Sweden also had a diarrhea group. The cluster analysis yielded slightly more disparate results but a healthy group was present in all populations. All four populations had an IBS and/or bowel dysfunction cluster identified; a gastroesophageal reflux cluster was also present in all countries.
  
  
  CONCLUSIONS
  The similarity of factor and cluster structures found in these four nations suggest that patterns of GI symptoms and groupings of individuals are similar across these Western cultures. These results are consistent with the current international Rome classification for separate upper and lower functional GI disorders.
authors.affiliation: Department of Medicine, University of Sydney, Nepean Hospital, Penrith, New South Wales, Australia.
authors.forename: N J
authors.initials: NJ
authors.lastname: Talley
authors.forename: G
authors.initials: G
authors.lastname: Holtmann
authors.forename: L
authors.initials: L
authors.lastname: Agréus
authors.forename: M
authors.initials: M
authors.lastname: Jones
mesh_terms: D000328:Adult; D001315:Australia; D016000:Cluster Analysis; D003109:Colonic Diseases, Functional / Q000150:complications; D003248:Constipation / Q000150:complications; D003967:Diarrhea / Q000150:complications; D004415:Dyspepsia / Q000150:complications; D005163:Factor Analysis, Statistical; D005260:Female; D005764:Gastroesophageal Reflux / Q000150:complications; D005767:Gastrointestinal Diseases / Q000150:complications*; D005858:Germany; D006801:Humans; D008297:Male; D008875:Middle Aged; D008910:Minnesota; D011795:Surveys and Questionnaires; D013548:Sweden