Is functional dyspepsia just a subset of the irritable bowel syndrome?

To determine whether functional dyspepsia and irritable bowel syndrome are different entities, epidemiological data, factor analysis studies, physiolo gical data and associated psychological symptoms were reviewed. Between 30% and 60% of patients with either diagnosis also meet the criteria for the o ther diagnosis, a level greater than expected to occur by chance but not su fficient to infer an identity. Most factor analysis studies identify indepe ndent clusters of symptoms corresponding to functional dyspepsia and irrita ble bowel syndrome. Visceral hypersensitivity is seen throughout the gastro intestinal tract in both disorders, but the motility patterns seen in assoc iation with functional dyspepsia (principally antral hypomotility and delay ed gastric emptying) differ from the motility patterns seen in irritable bo wel syndrome. Psychological symptoms are similar in these two disorders but are not believed to be aetiological for either of them. Thus, based on a f actor analysis of gastrointestinal symptoms and differences in intestinal m otility, functional dyspepsia and irritable bowel syndrome appear to be dif ferent entities.