Validity of a two-item screen for early psychosis

Abstract

Well-validated screening tools have been developed to identify people at high risk for psychosis, but these are rarely used outside of specialty clinics or research settings. The development of extremely brief and simple screening tools could increase dissemination, especially in settings with low buy-in such as those with low base rates of psychosis and/or time constraints. We sought to identify such a brief measure by modeling participant responses to three psychosis screening questionnaires (Prime Screen; Prodromal Questionnaire-Brief; Youth Psychosis At Risk Questionnaire) in a sample of 139 help-seeking individuals and 335 college students (age range: 12-25). Two screening questions with especially strong information characteristics were identified: "Do you see things that others can’t or don’t see?" and "Have you ever felt that someone was playing with your mind?" (Alternative two-item screens with similarly strong properties were also identified and validated using uncertainty quantified through Bayesian modeling.) The resulting measure was validated against clinician ratings of psychosis. The screen performed with a sensitivity of 53% and specificity 98% for clinically significant hallucinations or delusions, and sensitivity of 32% and specificity 99% for identifying people in an early phase of psychosis (clinical high risk or first episode psychosis).

The Community Assessment of Psychic Experiences-Positive scale (CAPE-P15) accurately classifies and differentiates psychotic experience levels in adolescents from the general population

“…Our results support prior research showing that visual and auditory hallucinations, when assessed with the Prodromal Questionnaire-Brief Child Version (PQ-BC) [ 62 ], discriminate the latent trait in a sample of children aged 9 to 10 years [ 60 ]. Moreover, our findings are also in accordance with Phalen et al [ 63 ], who, in help-seeking adolescents and college participants, observed that these two dimensions were the most informative of PE when assessed using three psychosis screening tools: the Prime Screen [ 64 ], the Prodromal Questionnaire-Brief (PQ-B) [ 62 ], and the Youth Psychosis at Risk Questionnaire-Brief (YPARQ-B) [ 65 ]. Our results also mirror the findings reported by Kelleher et al [ 61 ], who found that these symptoms plus paranoid delusional experiences and feelings of being controlled by external forces were highly specific and sensitive for detecting PE in adolescents.…”

Prevalence of Individuals at Clinical High-Risk of Psychosis in the General Population and Clinical Samples: Systematic Review and Meta-Analysis

“…The findings are also conflicting [ 21 , 22 , 23 ]: a previous systematic review found that the prevalence of the CHR-P state ranged from 1–8% in educational settings [ 24 ]. A further knowledge gap relates to the impact of using pre-screening instruments before the CHR-P evaluation to enhance detection [ 25 , 26 ]. Finally, while the prevalence of CHR-P cases may be moderated by age [ 27 ], gender [ 1 ], or geographical location [ 28 ], the actual impact of these factors is undetermined.…”

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“…Our results support prior research showing that visual and auditory hallucinations, when assessed with the Prodromal Questionnaire-Brief Child Version (PQ-BC) [62], discriminate the latent trait in a sample of children aged 9 to 10 years [60]. Moreover, our findings are also in accordance with Phalen et al [63], who, in help-seeking adolescents and college participants, observed that these two dimensions were the most informative of PE when assessed using three psychosis screening tools: the Prime Screen [64], the Prodromal Questionnaire-Brief (PQ-B) [62], and the Youth Psychosis at Risk Questionnaire-Brief (YPARQ-B) [65]. Our results also mirror the findings reported by Kelleher et al [61], who found that these symptoms plus paranoid delusional experiences and feelings of being controlled by external forces were highly specific and sensitive for detecting PE in adolescents.…”