title: Schizoaffective disorder diagnosed according to different diagnostic criteria--systematic literature search and meta-analysis of key clinical characteristics and heterogeneity.
abstract: BACKGROUND
  Schizoaffective disorder is viewed as a heterogeneous diagnosis among psychotic illnesses. Different diagnostic systems differ in their definition with DSM (-IIIR, -IV, and -V) providing a narrower definition than RDC and ICD-10. It is unclear whether this difference is reflected in patient samples diagnosed according to different diagnostic systems.
  
  
  METHODS
  Exploratory study based on a systematic review of studies of schizoaffective disorder samples diagnosed by either RDC and ICD-10 (group of "broad criteria") or DSM-IIIR and -IV ("narrow criteria"); comparison (by Mann-Whitney-U-tests) of key characteristics, such as age, number of hospitalizations, or scores in psychometric tests, between more broadly and more narrowly defined schizoaffective disorder samples using standard deviations as a measurement of heterogeneity as well as weighted means and percentages. To reduce selection bias only studies including schizoaffective patient samples together with affective disorder and schizophrenia samples were selected.
  
  
  RESULTS
  55 studies were included, 14 employing RDC, 4 ICD-10, 20 DSM-IIIR, and 17 DSM-IV. Thirteen characteristics were compared: patients diagnosed according to broader criteria had fewer previous hospitalizations (2.2 vs. 5.4) and were both less often male (42 vs. 51%) and married (21 vs. 40%). Heterogeneity was similar in both groups but slightly higher in RDC and ICD-10 samples than in DSM-IIIR and -IV-samples: +4% regarding demographic and clinical course data and +13% regarding psychometric tests (pooled SD).
  
  
  CONCLUSIONS
  Secular trends and different designs may have confounded the results and limit generalizability. Some comparisons were underpowered.
  
  
  CONCLUSIONS
  Differences in diagnostic criteria are reflected in key characteristics of samples. The association of larger heterogeneity with wider diagnostic criteria supports employing standard deviations as a measurement of heterogeneity.
authors.affiliation: Department of Psychiatry and Psychotherapy, University of Cologne Medical School, Cologne, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Pagel
authors.affiliation: Institute of Medical Statistics, Informatics, and Epidemiology, University of Cologne Medical School, Cologne, Germany.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Franklin
authors.affiliation: Department of Psychiatry and Psychotherapy, University of Cologne Medical School, Cologne, Germany. Electronic address: cbaethge@uni-koeln.de.
authors.forename: Christopher
authors.initials: C
authors.lastname: Baethge
mesh_terms: D000328:Adult; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D038801:International Classification of Diseases; D008297:Male; D008875:Middle Aged; D011618:Psychotic Disorders / Q000145:classification / Q000175:diagnosis* / Q000523:psychology
keywords: Diagnosis; Heterogeneity; Nosology; Psychosis; Schizoaffective disorder