title: The prevalence, diagnostic significance and demographic characteristics of Schneiderian first-rank symptoms in an epidemiological sample of first-episode psychoses.
abstract: BACKGROUND
  The diagnostic significance of first-rank symptoms (FRSs) remains uncertain. Ethnic differences in FRSs may account for high rates of schizophrenia in minority groups. This study aims to examine the prevalence of FRSs in an epidemiological sample of first-episode psychoses stratified by relevant demographic variables.
  
  
  METHODS
  We identified everyone aged 16-64 presenting with their first psychosis over 2 years in 3 UK centres.
  
  
  RESULTS
  A total of 426 subjects had consensus diagnoses of DSM-IV and ICD-10 psychotic conditions. Thirty-eight percent (95% CI=33-42) reported FRSs; more frequent in those classified as having schizophrenia (DSM-IV: 55%, 95% CI=47-63; ICD-10: 51%, 95% CI=44-58) than those with affective psychoses (DSM-IV: 31%, 95% CI=22-39; ICD-10: 29%, 95% CI=21-38). FRSs in schizophrenia were more common in white British subjects, while in affective psychoses, they were more frequent in the black group. The sensitivities, specificities and positive predictive values for schizophrenia of FRSs were 55, 69 and 72% according to DSM-IV and 51, 71, 74% according to ICD-10, respectively. The sensitivities were higher in white British than in the black group.
  
  
  CONCLUSIONS
  FRSs were common but unhelpful for differentiating schizophrenia from other psychoses as they occurred frequently in both diagnoses. Phenomenological differences did not explain the higher incidence of schizophrenia in black ethnic minority groups.
authors.affiliation: Department of Social Medicine, Toho University School of Medicine, Tokyo, Japan.
authors.forename: Kazushige
authors.initials: K
authors.lastname: Ihara
authors.forename: Craig
authors.initials: C
authors.lastname: Morgan
authors.forename: Paul
authors.initials: P
authors.lastname: Fearon
authors.forename: Paola
authors.initials: P
authors.lastname: Dazzan
authors.forename: Arsime
authors.initials: A
authors.lastname: Demjaha
authors.forename: Tuhina
authors.initials: T
authors.lastname: Lloyd
authors.forename: James B
authors.initials: JB
authors.lastname: Kirkbride
authors.forename: Hazel
authors.initials: H
authors.lastname: Hayhurst
authors.forename: Robin M
authors.initials: RM
authors.lastname: Murray
authors.forename: Peter B
authors.initials: PB
authors.lastname: Jones
mesh_terms: D000293:Adolescent; D000328:Adult; D003710:Demography; D003937:Diagnosis, Differential; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D038801:International Classification of Diseases; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011618:Psychotic Disorders / Q000175:diagnosis* / Q000453:epidemiology* / Q000523:psychology; D012559:Schizophrenia / Q000175:diagnosis / Q000453:epidemiology; D012720:Severity of Illness Index; D055815:Young Adult