title: The latent structure of the functional dyspepsia symptom complex: a taxometric analysis.
abstract: Rome III introduced a subdivision of functional dyspepsia (FD) into postprandial distress syndrome and epigastric pain syndrome, characterized by early satiation/postprandial fullness, and epigastric pain/burning, respectively. However, evidence on their degree of overlap is mixed. We aimed to investigate the latent structure of FD to test whether distinguishable symptom-based subgroups exist.
  
  
  
  Consecutive tertiary care Rome II FD patients completed the dyspepsia symptom severity scale. Confirmatory factor analysis (CFA) was used to compare the fit of a single factor model, a correlated three-factor model based on Rome III subgroups and a bifactor model consisting of a general FD factor and orthogonal subgroup factors. Taxometric analyses were subsequently used to investigate the latent structure of FD.
  
  
  
  Nine hundred and fifty-seven FD patients (71.1% women, age 41 ± 14.8) participated. In CFA, the bifactor model yielded a significantly better fit than the two other models (χ² difference tests both p < 0.001). All symptoms had significant loadings on both the general and the subgroup-specific factors (all p < 0.05). Somatization was associated with the general (r = 0.72, p < 0.01), but not the subgroup-specific factors (all r < 0.13, p > 0.05). Taxometric analyses supported a dimensional structure of FD (all CCFI<0.38).
  
  
  
  We found a dimensional rather than categorical latent structure of the FD symptom complex in tertiary care. A combination of a general dyspepsia symptom reporting factor, which was associated with somatization, and symptom-specific factors reflecting the Rome III subdivision fitted the data best. This has implications for classification, pathophysiology, and treatment of FD.
authors.affiliation: Department of Clinical and Experimental Medicine, Translational Research Centre for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Van Oudenhove
authors.affiliation: Department of Clinical Psychology and Psychotherapy, Johannes Gutenberg University, Mainz, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Jasper
authors.affiliation: Health Psychology, University of Leuven, Leuven, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Walentynowicz
authors.affiliation: Department of Clinical Psychology and Psychotherapy, Johannes Gutenberg University, Mainz, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Witthöft
authors.affiliation: Health Psychology, University of Leuven, Leuven, Belgium.
authors.forename: O
authors.initials: O
authors.lastname: Van den Bergh
authors.affiliation: Department of Clinical and Experimental Medicine, Translational Research Centre for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Tack
mesh_terms: D015746:Abdominal Pain / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002965:Classification; D004415:Dyspepsia / Q000145:classification* / Q000175:diagnosis* / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009325:Nausea / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology; D019518:Postprandial Period / Q000502:physiology; D011795:Surveys and Questionnaires; D063128:Tertiary Health Care / Q000145:classification / Q000379:methods; D055815:Young Adult
keywords: epigastric pain syndrome; factor analysis; functional dyspepsia; functional gastrointestinal disorders; postprandial distress syndrome; taxometric analysis