title: Empirically derived symptom sub-groups correspond poorly with diagnostic criteria for functional dyspepsia and irritable bowel syndrome. A factor and cluster analysis of a patient sample.
abstract: OBJECTIVE
  To determine how clusters (groups) of patients with respect to symptoms compare with a clinical diagnosis in patients with irritable bowel syndrome and non-ulcer dyspepsia.
  
  
  METHODS
  All patients who attended a gastroenterology practice at Nepean Hospital were included in the study. All patients received the previously validated Bowel Disease Questionnaire, and were independently assessed by the gastroenterologist. Factor analysis and a k-means cluster analysis were completed.
  
  
  RESULTS
  The study population comprised 897 patients [320 males (36%) and 577 females (64%)]. Factor analysis identified nine symptom factors: (1) diarrhoea; (2) constipation; (3) dysmotility; (4) dyspepsia/reflux; (5) nausea/vomiting; (6) bowel; (7) meal-related pain; (8) weight loss; and (9) abdominal pain. A k-means cluster analysis identified seven distinct subject groups, which included an undifferentiated group: (1) diarrhoea; (2) meal-related pain; (3) abdominal pain; (4) faecal indicators; (5) nausea/vomiting/weight loss; and (6) constipation. The majority of irritable bowel syndrome patients fitted into two cluster groups [diarrhoea (25%) and constipation (20%)], whereas those with non-ulcer dyspepsia predominantly fitted into the undifferentiated cluster (34%) and the nausea/vomiting cluster (18%).
  
  
  CONCLUSIONS
  This study supports the concept of symptom subgroups, including the subdivision of patients into diarrhoea- and constipation-predominant irritable bowel syndrome.
authors.affiliation: Department of Medicine, The University of Sydney, Nepean Hospital, Penrith, NSW, Australia.
authors.forename: G D
authors.initials: GD
authors.lastname: Eslick
authors.forename: S C
authors.initials: SC
authors.lastname: Howell
authors.forename: J
authors.initials: J
authors.lastname: Hammer
authors.forename: N J
authors.initials: NJ
authors.lastname: Talley
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016000:Cluster Analysis; D004415:Dyspepsia / Q000175:diagnosis*; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged