Longitudinal and cross-sectional validation of the WERCAP screen for assessing psychosis risk and conversion

Background: The Washington Early Recognition Center Affectivity and Psychosis (WERCAP) Screen was developed to assess risk for developing psychosis. Its validity has not been investigated in a large population-based study or with longitudinal analyses. Methods: 825 participants, aged 14-25, were recruited from Kenya. Symptoms were assessed using the WERCAP Screen, as experienced over the prior 3-months (3MO), 12-months (12MO) or lifetime (LIF). ROC curve analysis was used to determine the validity of the WERCAP Screen against the Structured Interview of Psychosis-Risk Syndromes. Longitudinal validity was assessed by comparing baseline p-WERCAP scores in psychotic disorder converters and non-converters, and using ROC curve analysis. Relationship of the p-WERCAP was examined against clinical variables. Results: ROC curve analyses against SIPS showed an AUC of 0.83 for 3MO, 0.79 for 12MO and 0.65 for LIF psychosis scores. The optimal cut-point on 3MO was a score of >12 (sens: 0.78; spec: 0.77; ppv: 0.41), and >32 for 12MO (sens: 0.71; spec: 0.74; ppv: 0.24). Baseline 3MO scores (but not LIF scores) were higher in converters compared to high-risk non-converters (p = 0.02). 3MO scores against conversion status had an AUC of 0.75, with an optimal cutoff point of >16 (sens: 1.0; spec: 0.53). All p-WERCAP scores significantly correlated with substance use and stress severity. 12 MO scores were most related to cognitive impairment. Conclusions: The WERCAP Screen is a valid instrument for assessing psychosis severity and conversion risk. It can be used in the community to identify those who may require clinical assessment and care, and for recruitment in psychosis-risk research.