Purpose: 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. Conclusion: 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.
Social Psychiatry and Psychiatric Epidemiology, 2013, Vol 48, Issue 12, p. 1917-1922