[Psychometric properties of dimensional measures derived from the latest German version of the Schedules for Clinical Assessment in Neuropsychiatry 2.1]

Abstract

Background: The Schedules for Clinical Assessment in Neuropsychiatry (SCAN) is a comprehensive set of clinical assessment instruments developed by the World Health Organisation. This is the first study to report psychometric properties of dimensional measures derived from the latest German version SCAN 2.1.

Methods: Within a randomized controlled trial comparing psychiatric day-hospital treatment to inpatient treatment, 202 acute mentally ill patients were interviewed by clinically experienced interviewers. Forty-seven items of Part I of SCAN 2.1 were selected for constructing dimensional measures. Six scales were generated using principal component analyses (PCA). They were compared to five scales constructed according to the items' affiliation to specific sections of SCAN 2.1.

Results and conclusions: Cronbach's alpha coefficients qualify the reliability of most scales as moderate (0.50<alpha<0.70) or substantial (alpha>0.70). With respect to high correlations between the scales generated using PCA and the section-specific scales, using the latter is recommended. Research into psychotic disorders, however, is missing, given that the present analyses are based on items from Part I of SCAN 2.1 only.