Gastrointestinal symptoms and subjects cluster into distinct upper and lower groupings in the community: A four nations study

OBJECTIVE: It is unknown whether distinct functional GI (GI) symptom groupi ngs occur in the general population and whether these are similar across di fferent cultures. Although symptom-based diagnostic criteria have been deve loped for upper and lower GI syndromes (the Rome criteria), the classificat ion is controversial. We aimed to identify whether independent symptom-base d subgroups exist in four countries consistent with the Rome criteria. METHODS: Random samples of the community were mailed a validated questionna ire based on the Bowel Disease Questionnaire in Rochester, MN (n = 2220), i n Sydney, Australia (n = 1135), and in Essen, Germany (n = 500). A differen t validated questionnaire was mailed to a random sample in Osthammar, Swede n (n = 1517). Only the common questions (n = 22) were used in the current a nalysis, and these were essentially identical in wording. The underlying st ructure of the item responses was examined using factor analysis. Initial f actors 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 nonresponder s were similar sociodemographically. All four studies yielded similar facto r structures. All countries reported symptom groupings consistent with the irritable bowel syndrome (IBS), dyspepsia and/or gastroesophageal reflux, a nd constipation; all except Sweden also had a diarrhea group. The cluster a nalysis yielded slightly more disparate results but a healthy group was pre sent in all populations. All four populations had an IBS and/or bowel dysfu nction cluster identified; a gastroesophageal reflux cluster was also prese nt 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 individ uals are similar across these Western cultures. These results are consisten t with the current international Rome classification for separate upper and lower functional GI disorders. (Am J Gastroenterol 2000;95: 1439-1447. (C) 2000 by Am. Coll. of Gastroenterology).