title: Irritable bowel syndrome subtypes according to bowel habit: revisiting the alternating subtype.
abstract: BACKGROUND
  Disturbed bowel habit, diarrhoea or constipation is a key manifestation of irritable bowel syndrome (IBS). In some patients, diarrhoea and constipation alternate, giving rise to the so-called alternating subtype.
  
  
  OBJECTIVE
  To assess IBS subtype breakdown (constipation (C-IBS), diarrhoea (D-IBS) or alternating (A-IBS)) according to the Rome II criteria and patients' self-assessment, the predominance in the alternating subtype (i.e. constipation, diarrhoea or neither), and the medical and personal impact, including health-related quality of life (HRQoL), of the different IBS subtypes.
  
  
  METHODS
  Two thousand individuals selected randomly to represent the general population were classified as potential IBS subjects (n = 281) or as non-potential IBS subjects (n = 1719) according to a validated questionnaire. Bowel habit classification was determined using the Rome II IBS supportive symptoms.
  
  
  RESULTS
  Among 201 subjects meeting the Rome I criteria, 15% presented with D-IBS, 44% presented with C-IBS, 19% presented with A-IBS, and 22% presented with normal bowel habit. Among the 63 subjects meeting the Rome II criteria, 23% presented with A-IBS. According to the subjects' self-assessment, of those meeting the Rome I criteria, 16% considered themselves to have D-IBS, 66% to have C-IBS and 18% to have A-IBS. In subjects meeting the Rome II criteria, 24% considered themselves to have A-IBS. Among those classified with A-IBS by the Rome II criteria, most considered themselves to be constipated. Regardless of the subtype self-classification, most subjects reported a normal frequency of bowel movements. Clinical manifestations in A-IBS were very similar to those of C-IBS but with the added presence of defecatory urgency. Abdominal discomfort/pain and frequency of visits to physicians were greater in the A-IBS subtype than in the other two IBS subtypes. HRQoL was affected similarly in all IBS subtypes.
  
  
  CONCLUSIONS
  Approximately one-quarter of subjects with IBS belong to the A-IBS subtype by the Rome II criteria, although the majority consider themselves to be constipated; indeed, clinical manifestations are more akin to the C-IBS subtype than to the D-IBS subtype. Abdominal discomfort/pain and frequency of visits to physicians are greater in the A-IBS subtype than in the other two IBS subtypes, while HRQoL is impaired similarly.
authors.affiliation: Institute of Functional and Motor Digestive Disorders, Centro Médico Teknon, C/Vilana 12, 08022 Barcelona, Spain. fmearinm@meditex.es
authors.forename: Fermín
authors.initials: F
authors.lastname: Mearin
authors.forename: Agustín
authors.initials: A
authors.lastname: Balboa
authors.forename: Xavier
authors.initials: X
authors.lastname: Badía
authors.forename: Eva
authors.initials: E
authors.lastname: Baró
authors.forename: Ellen
authors.initials: E
authors.lastname: Caldwell
authors.forename: Mercedes
authors.initials: M
authors.lastname: Cucala
authors.forename: Manuel
authors.initials: M
authors.lastname: Díaz-Rubio
authors.forename: Arturo
authors.initials: A
authors.lastname: Fueyo
authors.forename: Julio
authors.initials: J
authors.lastname: Ponce
authors.forename: Montse
authors.initials: M
authors.lastname: Roset
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Talley
mesh_terms: D000293:Adolescent; D000328:Adult; D003109:Colonic Diseases, Functional / Q000145:classification* / Q000150:complications / Q000503:physiopathology; D003248:Constipation / Q000209:etiology / Q000503:physiopathology; D003967:Diarrhea / Q000209:etiology / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000503:physiopathology; D010342:Patient Acceptance of Health Care; D011788:Quality of Life