Validity and reliability of the CAPE: a self-report instrument for the measurement of psychotic experiences in the general population

Objective: General population longitudinal cohort studies have demonstrated the prognostic validity of self-reported psychotic experiences, but data on reliability and cross-validation with interview-based measures of these experiences are sparse. This study tested the reliability and validity of the Community Assessment of Psychic Experiences (CAPE42). Method: At baseline, the CAPE42 was used to measure the subclinical psychosis phenotype in a general population sample (n = 765). At follow-up (mean interval: 7.7 months), the Structured Interview for Schizotypy, Revised (SIS-R), the Brief Psychiatric Rating Scale (BPRS), and the CAPE42 were administered (n = 510). Results: Baseline self-reported dimensions of psychosis were specifically and independently associated with their equivalent interview-based dimension at follow-up (standardized effect sizes of 0.4-0.5) and with their equivalent self-reported measure (standardized effect sizes of 0.6-0.8). Conclusion: The results indicate that self-reported dimensions of psychotic experiences in general population samples appear to be stable, reliable and valid.