Purpose

Although the stability of current diagnostic criteria for people with First Episode Psychosis (FEP) is essential for treatment, it still remains poorly investigated. As its examination necessarily requires a prospective evaluation of diagnostic trajectories, the aims of the current longitudinal investigation were: (a) to assess diagnostic changes in an Italian FEP population treated within an "Early Intervention in Psychosis" service during a 2-year follow-up period, and (b) to identify potential sociodemographic and clinical moderators of diagnostic instability at entry.

Methods

All participants were FEP individuals, aged 12-35 years. Their primary diagnosis was formulated both at baseline and at the end of the follow-up. At entry, they also completed the Positive And Negative Syndrome Scale (PANSS) and the Global Assessment of Functioning (GAF) scale. As measure of diagnostic stability, the Kappa statistic was first calculated. The associations of diagnostic shift with baseline sociodemographic and clinical characteristics were then analyzed using a logistic model with the diagnostic change as dependent variable. Finally, a propensity score was calculated, based on logistic analysis results.

Results

221 (50.1 %) FEP participants changed their initial diagnosis. The highest prospective diagnostic stability was found for initial diagnosis of schizophrenia (93.9 %) and affective spectrum psychoses (92.4 %). Diagnostic instability was high for initial diagnosis of brief psychotic disorder (100 %), schizophreniform disorder (100 %) and psychotic disorder not otherwise specified (92.1 %). The best predictors of diagnostic change were previous contact with neuropsychiatry services, shorter duration of untreated psychosis and higher baseline levels of disorganization.

Conclusions

Diagnostic stability is crucial for treatment and clinical decision making. Addressing instability in FEP diagnoses and detecting its moderators at entry are important challenges for future diagnostic development of early psychosis.