OBJECTIVES

(1) Assessment of diagnostic stability of psychotic disorders or psychotic mood disorders from 6 weeks to 18 months after initiation of treatment in a representative first-episode psychosis (FEP) sample. (2) Comparison between those patients who shifted from DSM-IV schizophreniform disorder to schizophrenia or schizo-affective disorder and those whose diagnosis of schizophreniform disorder remained stable.

METHOD

The Early Psychosis Prevention and Intervention Centre (EPPIC) in Australia admitted 786 FEP patients from January 1998 to December 2000. Data were collected from patients' medical records (MRs) using a standardized questionnaire. Seven hundred four MRs were available, 36 of which were excluded owing to nonpsychotic diagnoses or a psychotic disorder due to a general medical condition. Of the remaining 668 patients, 176 (26.3%) were lost to follow-up. Four hundred ninety-two subjects were analyzed. Strategies to assure validity and reliability of diagnoses were applied.

RESULTS

The same diagnosis was made at baseline (< or = 6 weeks after admission into EPPIC) and 18 months for 69.9% of the patients. Among the most consistent diagnoses were schizophrenia (97.3%), schizoaffective disorder (94.1%), and bipolar disorder (83.2%); the least stable, as expected, was schizophreniform disorder (40.0%). In subjects with schizophreniform disorder at baseline, the best predictors of a shift from schizophreniform disorder to schizophrenia or schizoaffective disorder were a higher baseline Clinical Global Impressions-Severity of Illness scale score and lower premorbid Global Assessment of Functioning score, although the variance accounted for was small (R2 = .07).

CONCLUSIONS

A longitudinally based diagnostic process in FEP samples is needed, especially in schizophreniform disorder and bipolar disorder. However, a thorough initial assessment of patient and family by a specialized team of investigators regarding the kind and duration of patient symptoms may lead to high diagnostic stability, especially in schizophrenia and schizoaffective disorder, even in a FEP sample with a relatively short duration of untreated psychosis.