title: A prospective follow-up study of first-episode acute transient psychotic disorder in Latvia.
abstract: BACKGROUND
  Acute and transient psychotic disorder (ATPD) has been described as an acute psychosis with brief onset and polymorphous symptomatology (WHO, 1993). The study of ATPD is growing increasingly relevant as scientists start an active discussion of the possibility of changing the ATPD classification in the next International Classification of Diseases (ICD-11). The aims of this study were to describe the clinical features of the index episode of ATPD in patients in Latvia, to analyse the stability and longitudinal changes of the diagnosis, to explore potential correlations between the sociodemographic and disease characteristics and to describe stressful life events before the first ATPD episode.
  
  
  METHODS
  A prospective follow-up study of all first-time admitted patients from the Riga Centre of Psychiatry and Addiction Disorders who fulfilled the ICD-10 criteria for ATPD (WHO, 1993) during the 15-month period from 9 January 2010 to 30 March 2011 and followed up until 31 October 2012. Stressful life events, demographics and clinical features during the index episode were assessed.
  
  
  RESULTS
  One hundred two patients were admitted with first-episode ATPD. The majority were females (60.7%). Over an average 26.5-month follow-up period, 59.8% of the patients were not readmitted. The overall stability rate of ATPD diagnosis in our sample was 67.4% (p = 0.0001). In the subgroup of patients who were readmitted, 70.7% had their diagnosis converted to schizophrenia in subsequent visits. Stressful life events before the first episode were found in 49.0% of first-episode ATPD patients. Thought disorder was found to be the strongest statistically significant predictor of ATPD diagnosis conversation to schizophrenia (odds ratio 4.3), with high Wald's criterion (9.435) in binary logistic regression.
  
  
  CONCLUSIONS
  ATPD is prevalent in Latvia, with rather high overall stability rate. Combining these data from first-episode ATPD patients in Latvia with data from other countries may help predict the development of the disease and provide a basis for potential changes to ICD-11.
authors: Riga Centre of Psychiatry and Addiction Disorders, Tvaika str, 2, Riga LV 1005, Latvia. rusaka.m@gmail.com.
authors: Marija
authors: M
authors: Rusaka
authors: Elmārs
authors: E
authors: Rancāns