ICD-10 delineates Acute and Transient Psychotic Disorders (ATPD, F 23) as distinct from schizophrenia and affective psychosis. We investigated the descriptive epidemiology of ATPD and predictive validity of the diagnosis, compared its three-year outcomes with affective psychosis and schizophrenia, and explored whether acute onset and early remission identify a distinct good outcome subgroup in non-affective psychoses.

Between 1992-1994, all first-episode psychosis patients in Nottingham were identified and assigned an intake ICD-10 diagnosis. Patients were assessed three years later using established outcome measures and longitudinal diagnosis assigned. Multivariate analyses were conducted to determine whether acute onset and early remission predicted favourable three-year outcome in non-affective psychotic disorders.

Of 168 cases of first-episode psychosis, 112 received an intake diagnosis of non-affective psychoses (F20-29) and 32 (19%) of ATPD (F23). ATPD diagnosis was stable in women over three years, but not in men. Outcomes of ATPD were better than schizophrenia and similar to affective psychosis. In non-affective psychoses, favourable outcomes were a function of gender and good premorbid functioning rather than acute onset and early remission.

ICD-10 ATPD criteria identify a diagnostically unstable group of disorders consisting of ‘good outcome’ schizophrenia, affective psychosis and a very small group of ‘true’ non-affective, non-schizophrenic acute and transient psychoses. Although ATPD have a better outcome than schizophrenia, in non-affective psychoses, acute onset and early remission do not independently predict favourable outcome over three years.