[Evaluation of Factor Structure and Construct Validity of the 12-Item Short Version of the OPD Structure Questionnaire (OPD-SQS) in Psychosomatic Patients].

BACKGROUND: Screening for personality dysfunction is regarded as increasingly important for treatment planning in clinical settings as this allows to determine specific clinical pathways in an early stage. Recently, the 12-item OPD Structure Questionnaire (OPD-SQS) was developed for this purpose and initial results of the factor structure and validity have been published. This study aimed to investigate and validate the OPD-SQS in further patient samples beyond the team of developers and to provide reference values.

METHODS: Data was assessed in psychosomatic outpatients (N=565) and inpatients (N=670) at Charité - Universitätsmedizin Berlin between 2012 and 2016. To examine the factor structure of the OPD-SQS confirmatory factor analyses (CFA) were applied in both samples. To evaluate construct validity, a SKID-II-Interview was performed in N=105 patients and narcissism inventory (NI-90) was completed by N=160 patients. In addition, a range of instruments reflecting emotional, social and physical health were assessed. Bivariate correlations were performed to analyze relations between these instruments and the OPD-SQS.

RESULTS: CFAs indicated a good to satisfying fit for the proposed model including 3 factors. A Bifactormodel resulted in very good modelfit. Analyses of construct validity resulted in high positive correlations of OPD-SQS with dimensional SCID-II scores, SKID-II interviews, and NI-90 confirming convergent validity. Results for discriminant validity were heterogeneous. Medium to high correlations were found with a range of instruments including D-CAT (depression), A-CAT (anxiety), S-CAT (stress), and PHQ-15 (somatic symptoms). Subsequent analyses revealed, that the factor self-perception is potentially being influenced by current depression and anxiety. Analyses showed only minor differences of correlations between OPD-SQS subscales and other instruments.

CONCLUSIONS: The OPD-SQS seems to be appropriate for screening of personality dysfunction. However, other aspects of psychopathology are gathered in addition. Therefore, further investigation of the patients' personality structure such as an OPD interview may be added in clinical settings.