Determining the cumulative incidence of treated schizophrenia and predictors of transition in an early intervention for psychosis service

Area of Science:

• Psychiatry
• Epidemiology
• Public Health

Background:

• Accurate schizophrenia incidence measurement informs public policy and resource allocation.
• First contact diagnoses underestimate true incidence due to later transitions to schizophrenia.
• This study addresses the need for precise schizophrenia incidence data.

Purpose of the Study:

• Determine the 24-month cumulative incidence of treated DSM-5 schizophrenia in first episode psychosis (FEP) cases.
• Quantify the underestimation of schizophrenia incidence using only first contact cases.
• Identify the proportion and predictors of transition to schizophrenia or bipolar disorder.

Main Methods:

• Observational study of 1220 FEP cases aged 15-24 at the Early Psychosis Prevention and Intervention Centre (EPPIC) service (2011-2016).
• Prospective data recording with retrospective collection.
• Poisson and Cox regression analyses for incidence rate ratios and hazard ratios.

Main Results:

• At presentation, 17.2% of FEP cases had schizophrenia; this rose to 30.2% after a median of 93 weeks.
• Cumulative incidence of schizophrenia was 57% higher than first contact diagnosis (IRR = 1.57).
• At discharge, 30.2% met criteria for schizophrenia and 16.3% for bipolar disorder.

Conclusions:

• The cumulative incidence method provides a more accurate measure of schizophrenia incidence.
• Findings highlight the importance of considering diagnostic transitions in FEP.
• Accurate incidence data is crucial for effective public health planning and resource management.