Acute and transient psychotic disorder (ATPD; F23, ICD-10) have been described as acute psychosis with brief onset, polymorphous symptomatology and rapid resolution. ATPD is not very well studied disorder and it has not been studied in Latvia up to now.

Retrospective chart review study of all first time hospitalised patients fulfilling ICD-10 criteria for ATPD treated at the Riga Centre of Psychiatry and Addiction Disorders, Latvia during a 3-year period. Patients were assessed using standardised instruments during 4.1 years follow-up period.

During a 3-year period 294 patients were first time hospitalized with ATPD. Over an average of 4.1 years follow-up period 62% (182) of patients were not rehospitalised. In the subgroup of rehospitalised patients diagnosis in 71% (80) of them later changed to schizophrenia. Comparing ATPD subgroups we found that the percentage of patients “with schizophrenic symptoms” (F23.1) was higher 55% (161). ATPD “without schizophrenic symptoms” (F23.0) diagnosis was more frequent for “pure” ATPD patients 79% (38), than for ATPD, which later developed into schizophrenia (p < 0.001). Clinical features like affective disturbance was present in 25%, anxiety 58% and hallucinations in 53% of patients, who later developed schizophrenia and only in 24% with “pure” ATPD (p < 0.001).

More than half of the patients were hospitalized once during follow-up period. In subgroup of rehospitalised patients most common diagnostic change was to schizophrenia. Further prospective research on the topic is warranted to understand evaluation of the diagnosis in ICD-10 and possible changes in ICD-11.