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Usefulness of the CAPE-P15 for detecting people at ultra-high risk for psychosis: Psychometric properties and cut-off values

Schizophrenia Research, In Press, Corrected Proof, Available online 27 February 2017, Available online 27 February 2017

Abstract

A need for a brief, easy to complete self-report questionnaire to detect people at ultra-high risk for psychosis (UHR) in busy clinical settings has been recognised. Our aim was to explore whether the Community Assessment of Psychic Experiences – Positive 15-items Scale (CAPE-P15) could be used as a screening tool to identify people at UHR in a clinical setting. Our objectives were to confirm the CAPE-P15 factorial structure as well as its reliability and determine cut-off values for the detection of such individuals using the Comprehensive Assessment of At-Risk Mental States (CAARMS), a commonly used clinical interview for the detection of UHR. 165 participants aged between 13 and 18 referred to the General Hospital of Vienna were included in the analysis. 50.9% of the sample were “CAARMS-positive” and 49.1% “CAARMS-negative”. The Youden method determined CAPE-P15 cut-off values for UHR detection of 1.47 for both frequency of and distress associated with psychotic experiences. The cut-off value of 1.47 for frequency showed sensitivity of 77%, specificity of 58%, a positive predictive value of 66% and a negative predictive value of 71%; whilst for distress it showed sensitivity of 73%, specificity of 63%, a positive predictive value of 69% and a negative predictive value of 66%. Good reliability and the previously suggested three-correlated factor model as well as an alternative bi-factor model of the CAPE-P15 were confirmed. The CAPE-P15 seems to be a promising screening tool for identifying people who might be at UHR in busy clinical settings.

Keywords: CAARMS, CAPE, CAPE-P15, Psychosis, Screening, Ultra-high risk.

Footnotes

a Department of Psychiatry, University of Cambridge, Cambridge, Herchel Smith Building, CB2 0SZ Cambridge, UK

b Department of Psychiatry and Psychotherapy, Clinical Division of Social Psychiatry, Medical University Vienna, 1090 Vienna, Austria

c Orygen, National Centre of Excellence in Youth Mental Health, 3052 Parkville, Melbourne, VIC, Australia

d Centre for Youth Mental Health, University of Melbourne, 3052 Parkville, Melbourne, VIC, Australia

e Department of Child and Adolescent Medicine, Medical University Vienna, 1090 Vienna, Austria

f Department of Neurology, Alfred Krupp Hospital Rüttenscheid, 45131 Essen, Germany

g Department of Child and Adolescent Psychiatry, Medical University Vienna, 1090 Vienna, Austria

h Department of Psychiatry and Psychotherapy, Clinical Division of Biological Psychiatry, Medical University Vienna, 1090 Vienna, Austria

i Department of Psychiatry, University Hospital of Salamanca, IBSAL Neurosciences, University of Salamanca, 37007 Salamanca, Spain

j CAMEO Early intervention in Psychosis Services, Cambridgeshire and Peterborough NHS Foundation Trust, CB21 5EF Cambridge, UK

k Norwich Medical School, Faculty of Medicine and Health Sciences, University of East Anglia, NR4 7TJ Norwich, UK

Corresponding author at: Block 7, Ida Darwin Site, Fulbourn, Cambridge, CB21 5EE, UK.

1 Joint first authors.

2 Joint senior authors.