title: Diagnostic concordance in functional psychosis revisited: a study of inter-relationships between alternative concepts of psychotic disorder.
abstract: More than a decade ago, a series of retrospective studies examined the concordance between proliferating definitions of severe psychiatric disorder. The European response has been a poly-diagnostic one, which has attempted to maintain interest in a broad range of psychiatric phenomena in the psychoses. In North America a more convergent approach has emerged, resulting in a series of operational definitions evolving from one another, and a correspondingly limited capacity to allow alternative perspectives to co-exist. The present study uses a prospective design as well as recent improvements in the clinical validity of psychopathology assessment to re-evaluate the relationships between competing concepts of psychotic illness in a broad sample (N = 176) of recent-onset psychotic patients. In the schizophrenic group, concordance was predictably highest among recent North American 'cousins', and lowest among various historical concepts. There was a moderately high concordance between selected schizoaffective and atypical psychosis definitions, indicating that this component is an important area for further studies of descriptive validity. These interrelationships may be used as a starting point to explore latent classes underlying the phenomena of functional psychosis.
authors.affiliation: National Health and Medical Research Council Schizophrenia Research Unit, Royal Park Hospital, Melbourne, Australia.
authors.forename: P D
authors.initials: PD
authors.lastname: McGorry
authors.forename: B S
authors.initials: BS
authors.lastname: Singh
authors.forename: S
authors.initials: S
authors.lastname: Connell
authors.forename: D
authors.initials: D
authors.lastname: McKenzie
authors.forename: R J
authors.initials: RJ
authors.lastname: Van Riel
authors.forename: D L
authors.initials: DL
authors.lastname: Copolov
mesh_terms: D000328:Adult; D003702:Delusions / Q000145:classification / Q000175:diagnosis / Q000523:psychology; D005260:Female; D006212:Hallucinations / Q000145:classification / Q000175:diagnosis / Q000523:psychology; D006801:Humans; D008297:Male; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data*; D011594:Psychometrics; D011618:Psychotic Disorders / Q000145:classification / Q000175:diagnosis* / Q000523:psychology; D012559:Schizophrenia / Q000145:classification / Q000175:diagnosis; D012565:Schizophrenic Psychology; D013850:Thinking