The diagnosis of psychotic disorders is based on the presence or absence of characteristic symptoms. However the presence of such symptoms varies during the course and treatment of these illness, which raises the question of how stable a diagnosis of psychotic disorder remains over time.

The aim of this study was to assess the 3-year diagnostic stability after first admission for psychotic disorders.

We performed a retrospective study at the Department of Psychiatry of Centro Hospitalar S.João (Porto, Portugal). Patients were admitted in the inpatient unit from 2007 to 2010 (n=59), for a first psychotic episode experience and fulfilled criteria for one of the following diagnosis: Schizophrenia, Schizoaffective Disorder, Bipolar Affective Disorder, Psychotic Disorder due to Substance Use, Acute and Transient Psychotic Disorders and Psychosis NOS (ICD-10). The diagnoses were extracted from clinical records, and reassessed three years after the initial diagnosis. Twenty patients were lost to follow-up and thus excluded from the study.

In our sample, 69.2% of the subjects kept the same diagnosis three years later and 30.8% were given a different diagnosis at follow-up. Schizophrenia and Bipolar Affective Disorder were the most stable diagnoses and Psychosis not otherwise specified and Acute and Transient Psychotic Disorder were more variable.

Diagnosis performed in the first episodes of mental disorders has important therapeutic and prognostic implications. With its characteristic fluctuating symptomatology, first episode psychosis may be more vulnerable to diagnostic change over time.