M97. PREDICTORS OF TRANSITION TO SCHIZOPHRENIA IN BRIEF PSYCHOTIC DISORDER: FINDINGS FROM A 3-YEAR LONGITUDINAL STUDY IN THE PAFIP COHORT

BACKGROUND: The category ‘brief psychotic disorder’ (BPD) is defined in the Diagnostic and Statistical Manual of Mental Disorders (DSM) as a short-lived psychotic condition in which delusions, hallucinations, disorganised speech or grossly disorganised or catatonic behaviour are present for at least 1 day but less than 1 month. BPD is a relatively uncommon disease accounting for 2–7% of first-episode psychoses (FEP) and it has been poorly investigated in comparison with other psychotic disorders, probably due to its low prevalence and associated good prognosis. However, FEP patients with BPD have low diagnostic stability at follow-up and a high transition rate (around 55%) to long-lasting psychotic disorders, mainly to schizophrenia. This study explored the proportion of diagnostic transition to schizophrenia after 3 years in a cohort of FEP patients with BPD, to determine whether there were early predictive factors for such transition in this BPD population. METHODS: A 36-month prospective observational study of patients with first-episode BPD was conducted. The sample included subjects aged 18–60 from the intervention programme of first-episode psychosis non-affective psychosis (PAFIP) of the University Hospital Marques de Valdecilla (Spain). BPD diagnoses were confirmed using the Structured Clinical Interview for DSM-IV (SCID-I) at 6 months following admission into the PAFIP programme. Sociodemographic, premorbid and baseline clinical variables were collected and patients were followed over 3 years while they received treatment in the PAFIP programme. A DSM-IV diagnostic reassessment was performed on those patients who completed the follow-up and subjects were classified according to whether or not they had developed schizophrenia after 3 years. Univariate screening was performed to determine variables eligible for the predictive model, and factors that reached statistical or marginal significance (p ≤ 0.1) were selected for multivariate logistic regression analysis. Significant statistical level was set at 0.05. All statistical evaluation was performed using MedCalc Statistical Software (version 19.0.7). RESULTS: Of the 569 patients enrolled in the PAFIP programme between 2001 and 2018, 59 met the criteria for BPD. Of those, 40 (67.8%) completed the 36-month follow-up and 16 (40%) maintained their initial BPD diagnosis. Among the patients who developed other mental disorders by the end of the study period (60%; n = 24), the proportion of transition to schizophrenia was 62.5% (n = 15). Being younger at psychosis onset, living alone, a poor premorbid adjustment, acute onset of psychotic symptomatology, and higher severity of hallucinatory behaviour were variables that showed univariate associations with subsequent development of schizophrenia. A multivariate logistic regression model revealed that transition to schizophrenia was independently significantly associated with younger age at psychosis onset (OR = 0.83, 95% CI 0.69–0.99; p = 0.048), living alone (OR = 14.3, 95% CI 1.09–186.77; p = 0.042) and greater hallucinatory activity (OR = 1.81, 95% CI 1.07–3.07; p = 0.028). DISCUSSION: Our main findings were that 37.5% of patients who presented an initial BPD diagnosis developed schizophrenia in the following 36 months. Being younger at psychosis onset, living alone and experiencing greater hallucinatory activity at baseline were independent predictors of diagnostic transition to schizophrenia in this BPD population. Individuals with BPD presenting these risk factors should therefore be targeted for intensive interventions similar to those performed on patients with first-episode schizophrenia.