OBJECTIVE: Despite various models examining baseline factors, predicting outcomes in individuals at clinical high risk for psychosis (CHR-P) remains challenging. Specifically, neglecting factors like ongoing antipsychotic (AP) medications introduce bias and reduce method precision. The main aim of this research was to determine if the presence of AP prescription at baseline identifies a CHR-P subgroup with worse prognostic outcomes over a 2-year period. METHODS: A group of 180 FEP individuals (92 CHR-P/AP+, 88 CHR-P/AP-) were evaluated at baseline and after 24 months using the PANSS and GAF scales. Individuals with baseline AP prescription were included in the CHR-P/AP+ subgroup
those not taking APs were grouped as CHR-P/AP-. Univariate Cox regression analysis and mixed-design ANOVA were performed. RESULTS: After 2 years, CHR-P/AP+ had a higher rate of new hospitalization but lower rate of service disengagement. No significant inter-group difference in psychosis transition rate was found. A "time-×-group" interaction effect on longitudinal improvement in PANSS total score was observed in CHR-P/AP+ subjects. CONCLUSIONS: It is advisable to conduct a more extensive outcome evaluation beyond the psychometric criteria for CHR-P and the mere consideration of psychosis transition. Such an approach would facilitate the identification of specific CHR-P subgroups with divergent prognoses and different AP response.