M95. DSM-5 CLINICIAN-RATED DIMENSIONS OF PSYCHOSIS SYMPTOM SEVERITY: PSYCHOMETRIC PROPERTIES

BACKGROUND: In DSM-5, a number of “emerging measures” are included for further research and clinical evaluation. These patient assessment measures were developed to be administered at the initial patient interview and to monitor treatment progress. One of these instruments is the Clinician-Rated Dimensions of Psychosis Symptom Severity (CRDPSS). Using this instrument, a clinician can rate the severity of eight symptom dimensions of psychotic disorders. The psychometric properties and the applicability of the instrument in clinical practice have not yet been investigated. The current study aims to investigate the internal consistency, factor structure and external validity with other assessment instruments. METHODS: The CRDPSS measures eight symptom dimensions, namely Hallucinations, Delusions, Disorganized speech, Abnormal psychomotor behavior, Negative Symptoms, Impaired Cognition, Depression and Mania. Items are scored on a five-point scale ranging from “Not present” to “Present and Severe”. This interview has been applied in the Psychosis Recent Onset GRoningen Survey (PROGR-S), a diagnostic protocol for patients with a suspected recent-onset psychotic disorder (n = 164 in the current analysis). Besides the CRDPSS, scores on the Positive and Negative Syndrome Scale (PANSS), Health of Nations Outcome Measure (HoNOS), the Mongomery Asberg Depression Rating Scale (MADRS), Cambridge Cambridge Neuropsychological Test Automated Battery (CANTAB) and mini-Structural Clinical Assessment in Neuropsychiatry (mini-SCAN) were used for current analyses. The Crohnbach Alpha was calculated to investigate internal consistency, exploratory factor analysis was applied, and the convergent validity was investigated by calculating non-parametric correlations of the CRDPSS with similar items or subscales of the other instruments. RESULTS: The Cronbach’s alpha of the CRDPSS was 0.36, indicating low internal consistency. Factor analysis resulted in three Factors: 1. Delusions/Mania, 2. Abnormal psychomotor behavior/Negative Symptoms/Impaired cognition, 3. Hallucinations/Depression. For hallucinations, Delusions, and Depression a Kendall’s tau of 0.35 – 0.45 was observed with the other instrument scores and for Impaired cognition tau = 0.6, indicating a weak to moderate association. Negative symptoms resulted in tau < 0.2 and for the other instruments tau < 0.1, but in these cases the measure of the other instruments was of questionable quality. DISCUSSION: The internal consistency of the CRDPSS was poor and factor analysis resulted in factors that differed to some extent from previous findings. Moreover, the convergent validity with other instruments was poor to moderate. In conclusion, based on first analyses the reliability and clinical applicability of the CRDPSS appears limited. Future studies should investigate inter-rater reliability, test-retest reliability, use more optimal measures to investigate convergent validity and use larger samples.