Transition to schizophrenia in acute and transient psychotic disorders

Background The diagnostic category of acute and transient psychotic disorders (ATPD) was introduced in ICD-10. Subsequent studies have called into question its validity and reliability. Aims To determine the pattern of diagnostic revision to schizophrenia in first-ever diagnosed ATPD. Method Using data drawn from the Scottish Morbidity Record, we estimated incidence and diagnostic change in first-ever diagnosed ATPD in Scottish hospitals between January 1997 and December 2010 (n = 2923). Results The average incidence of ATPD was 4.1 per 100 000 population per year. Diagnostic stability was estimated at 53.9% over an average of approximately 4 years of observation. The most common diagnostic shift was to schizophrenia (12.6%), over an average of 1.7 years. Estimates of the transition risks for schizophrenia were 80% at 2.8 years and 90% at 4.6 years. Longer first admission to hospital, younger age at onset and male gender were associated with increased risk and earlier development of schizophrenia. Conclusions Routinely collected data suggest that approximately one in eight individuals with first-ever diagnosed ATPD will develop schizophrenia within 3-5 years. Those at high risk of transition may benefit from monitoring for possible diagnostic change.