Self-report questionnaires have been developed to efficiently assess psychosis risk and vulnerability. Despite this, the validity of these questionnaires for assessing specific positive symptoms in those at clinical high risk for psychosis (CHR) is unclear. Positive symptoms have largely been treated as a uniform construct in this critical population and there have been no reports on the construct validity of questionnaires for assessing specific symptoms. The present study examined the convergent, discriminant, and criterion validity of the Launay Slade Hallucination Scale-Revised (LSHS-R), Prodromal Questionnaire-Brief (PQB), and Community Assessment of Psychic Experiences positive scale (CAPE-P) using a multimethod approach. CHR individuals (N = 71) and healthy controls (HC; N = 71) completed structured clinical interviews, self-report questionnaires, and neuropsychological tests. Questionnaire intercorrelations indicated strong convergent validity (i.e., all rs > .50); however, evidence for discriminant validity was more variable. In examining relations to interviewer-assessed psychosis symptoms, all questionnaires demonstrated evidence of criterion validity, though the PQB showed the strongest convergent correlations (e.g., r = .48 with total symptoms). In terms of discriminant validity for specific positive symptoms, results were again more variable. PQB subscales demonstrated limited specificity with positive symptoms, whereas CAPE-P subscales showed some specificity and the LSHS-R showed high specificity. In addition, when correlations with internalizing and externalizing symptoms were examined, only the PQB showed consistent significant correlations. These results are interpreted in terms of the strengths and limitations of each measure, their value for screening, and their potential utility for clarifying differences between specific positive symptoms.
Keywords: Clinical high risk; Construct validity; Positive symptoms; Questionnaires.
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