Polythetic diagnostic approach to the borderline personality disorder. the valency of the single criterion in the concept of professional therapists.

The present study addresses the question whether the polythetic approach of ICD-10 and DSM-IV is useful in clinical practice for the diagnosis 'Borderline' personality disorder (BPD). A questionnaire containing all individual criteria for the 9 personality disorders and the schizotypal disorder used by the ICD-10, completed by the DSM-IV criteria for the BPD not covered by the ICD-10, was developed. Eight hundred therapists were asked to mark the importance of every single criterion for forming the diagnosis or for ruling out BPD. Our data analysis of the received questionnaires performed a rankscore based on an altered calculation of the mean value. The criteria which described the patients' instability in relationship and mood, and identity disturbances were seen as the most important features for the diagnosis of BPD. The criterion of cognitive disturbances, newly introduced in DSM-IV, was not felt to be a major clinical feature. In conclusion, our study reflects the results of other authors in the sense that a single criterion cannot be considered pathognomonic for BPD, but has greater importance and a higher priority in establishing the diagnosis BPD. This should be taken into account to reconsider the polythetic concept in favor of a hierarchical approach with core criteria.