title: Variations in incidence and age of onset of acute and transient psychotic disorders.
abstract: OBJECTIVE
  To determine incidence and age of onset of the ICD-10 category of 'acute and transient psychotic disorders' (ATPDs) characterised by subtypes with polymorphic, schizophrenic and predominantly delusional symptoms, pointing out differences from schizophrenia (SZ) and bipolar affective disorder (BD).
  
  
  METHODS
  We identified all subjects aged 15-64 years who were listed for the first time in the Danish Psychiatric Register with a diagnosis of ATPDs (n = 3,350), SZ (n = 4,576) and BD (n = 3,200) in 1995-2008. Incidence rates and rate ratios (IRR; 95 % confidence interval) by gender and age were calculated.
  
  
  RESULTS
  The incidence of ATPDs was 6.7 per 100,000 person-years, similarly high for both genders (IRR 1.0; 0.9-1.1). Among the ATPD subtypes, polymorphic psychotic disorder was more common in females (IRR 1.4; 1.2-1.6) as opposed to those featuring schizophrenic symptoms, which tended to occur in younger males (IRR 1.4; 1.2-1.7). No significant gender difference was found for acute predominantly delusional disorder (IRR 1.0; 0.9-1.2), which had a later onset than any ATPD subtypes. SZ had an incidence twice as high in males (IRR 2.0; 1.9-2.2), and an earlier age of onset than ATPDs. A different pattern was observed for BD in terms of a slightly greater incidence in females (IRR 1.1; 1.0-1.1), and a later age of onset than both ATPDs and SZ.
  
  
  CONCLUSIONS
  These findings are likely to reflect the heterogeneity of the clinical features encompassed by ATPDs, and contribute to building a case for their revision in ICD-11.
authors.affiliation: Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Skovagervej 2, 8240, Risskov, Denmark, augusto.castagnini@cpf.au.dk.
authors.forename: Augusto
authors.initials: A
authors.lastname: Castagnini
authors.forename: Leslie
authors.initials: L
authors.lastname: Foldager
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D017668:Age of Onset; D001714:Bipolar Disorder / Q000175:diagnosis / Q000453:epidemiology*; D003702:Delusions; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D038801:International Classification of Diseases; D008297:Male; D008875:Middle Aged; D011618:Psychotic Disorders / Q000145:classification / Q000175:diagnosis* / Q000453:epidemiology* / Q000523:psychology; D012042:Registries; D012563:Schizophrenia, Paranoid / Q000175:diagnosis / Q000453:epidemiology*; D017678:Sex Distribution; D013997:Time Factors; D055815:Young Adult