The Community Assessment of Psychic Experiences: Optimal cut-off scores for detecting individuals with a psychotic disorder

OBJECTIVES: The need for a brief screening tool for psychosis is widely recognized. The Community Assessment of Psychic Experiences (CAPE) is a popular self-report measure of psychosis, but a cut-off score that can detect those most likely to fulfill diagnostic criteria for psychotic disorder is not established.

METHODS: A case-control sample from the Genetic Risk and Outcome of Psychosis Project study (N = 1375, healthy individuals, n = 507, and individuals with a psychotic disorder, n = 868), was used to examine cut-off scores of the CAPE with receiver operating curve analyses. We examined 27 possible cut-off scores computed from a combination of scores from the frequency and distress scales of the various factors of the CAPE.

RESULTS: The weighted severity positive symptom dimension was most optimal in detecting individuals with a psychotic disorder (>1.75 cut-off; area under the curve = 0.88; sensitivity, 75%; specificity, 88%), which correctly identified 80% of the sample as cases or controls with a diagnostic odds ratio of 22.69.

CONCLUSIONS: The CAPE can be used as a first screening tool to detect individuals who are likely to fulfill criteria for a psychotic disorder. The >1.75 cut-off of the weighted severity positive symptom dimension provides a better prediction than all alternatives tested so far.