[The Operationalized Psychodynamic Diagnostics System (OPD-2): validity of the Axis I "Experience of illness and prerequisites for treatment"].

The Operationalized Psychodynamic Diagnostics System (OPD) was introduced in order to allow for operationalized and reproducible psychoanalytic diagnoses. A revised version of the instrument was published in 2006. Validation studies are lacking for its Axis I, in particular. The aim of the present study is to investigate the validity of Axis I, as well as to test the underlying factors for their plausibility. The instrument was applied to 263 inpatients by trained raters. For testing their validity, OPD measures were compared to a similar self-rating questionnaire (Questionnaire of measuring the motivation for psychotherapy). These measures corresponded well, and the intercategorial differences between different patient groups (split by sex, age and ICD-10 diagnosis) according to our expectations. Moreover, we established feasible factors. Thus, our results show good validity, and a plausible internal structure of the Axis I.