title: Impact of advertisement and clinic populations in symptoms and perception of irritable bowel syndrome.
abstract: BACKGROUND
  This study assessed the impact of recruitment on irritable bowel syndrome clinical trials, by determining whether irritable bowel syndrome patients recruited from advertisement or a specialty clinic differ in clinical and physiologic measures.
  
  
  METHODS
  We prospectively surveyed 657 irritable bowel syndrome patients who either: (i) were referred from a functional bowel disease clinic (52%); or (ii) responded to advertisement for clinical trials (48%), using questionnaires about bowel and psychological symptoms, and quality of life. In a subset of 42 irritable bowel syndrome patients (29 advertisement and 15 clinic patients), rectal discomfort thresholds were measured before and after repetitive sigmoid stimulation.
  
  
  RESULTS
  While the advertisement population more commonly consulted primary care physicians, the clinic population more commonly consulted gastroenterologists. The clinic population reported more prevalent and severe abdominal pain, and higher psychological symptom scores, while the advertisement population had greater quality of life. In the visceral perception studies, both subgroups were hypersensitive to rectal distension.
  
  
  CONCLUSIONS
  Compared to the clinic population, the advertisement population had less severe abdominal pain and psychological symptoms, better quality of life but similar visceral perception. The differences in clinical self-reports may have consequences for enrolment of these different patient populations into clinical trials.
authors.affiliation: UCLA/CURE/Digestive Disease Research Center Neuroenteric Disease Program, Departments of Medicine and Physiology, UCLA School of Medicine, Los Angeles, CA 90024, USA.
authors.forename: O Y
authors.initials: OY
authors.lastname: Lee
authors.forename: L Z
authors.initials: LZ
authors.lastname: Fitzgerald
authors.forename: B
authors.initials: B
authors.lastname: Naliboff
authors.forename: M
authors.initials: M
authors.lastname: Schmulson
authors.forename: C
authors.initials: C
authors.lastname: Liu
authors.forename: S
authors.initials: S
authors.lastname: Fullerton
authors.forename: E A
authors.initials: EA
authors.lastname: Mayer
authors.forename: L
authors.initials: L
authors.lastname: Chang
mesh_terms: D000328:Adult; D000329:Advertising; D003109:Colonic Diseases, Functional / Q000175:diagnosis* / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D018579:Patient Selection; D011446:Prospective Studies; D011788:Quality of Life / Q000523:psychology; D012007:Rectum / Q000502:physiology; D012812:Sigmoidoscopy / Q000009:adverse effects; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D013997:Time Factors