Outcome of first-episode acute and transient psychotic disorder in Hong Kong Chinese: a 20-year retrospective follow-up study

Background: Acute and transient psychotic disorder' (ATPD) is a category in ICD-10 marked by psychosis with acute onset and early remission. It remains relatively under-researched, despite controversies over its nosological status in the current classification system.Aims: (1) To assess the changes in diagnosis over time in patients initially diagnosed as ATPD. (2) To identify factors predicting changes in diagnosis, and compare the long-term outcomes of various patterns of diagnostic shift. (3) To make recommendations on the classification and treatment of ATPD based on the findings of the study.Methods: This was a retrospective longitudinal study based on review of medical records of patients first admitted to a regional hospital in Hong Kong for ATPD during the period from 1990-2000.Results: Of the 87 subjects initially diagnosed as ATPD, 64.4% had their diagnoses revised over an average of 20 years, mostly to bipolar disorder and schizophrenia. Among those with diagnosis of ATPD unchanged, 54.8% had one single episode, while the remaining 45.2% had recurrence. Subjects with diagnostic shift had significantly younger age of onset, more first-degree relatives with a history of mental illness, and more subsequent psychiatric admissions.Conclusions: ATPD is likely a composite category consisting of clinically distinct outcome groups, for which further research is warranted to identify diagnostic features that distinguish them at initial presentation and revise the current nosological status of ATPD. Long-term follow-up, judicial use of antipsychotics, and education on prognosis are of paramount importance in managing patients diagnosed with ATPD.