Determining essential dimensions for the clinical approximation of personality disorder severity: multi-method study.

BACKGROUND

Decades of research on the dimensional nature of personality disorder have led to the replacement of categorical personality disorder diagnoses by a dimensional assessment of personality disorder severity (PDS) in ICD-11, which essentially corresponds to personality functioning in the alternative DSM-5 model for personality disorders. Besides advancing the focus in the diagnosis of PD on impairments in self- and interpersonal functioning, this shift also urges clinicians and researchers worldwide to get familiar with new diagnostic approaches.

AIMS: This study investigated which PDS dimensions among different assessment methods and conceptualisations have the most predictive value for overall PDS.

METHOD: Using semi-structured interviews and self-reports of personality functioning, personality organisation and personality structure in clinical samples of different settings in Switzerland and Germany (n = 534), we calculated a latent general factor for PDS (g-PDS) by applying a correlated trait correlated (method - 1) model (CTC(M-1)).

RESULTS

Our results showed that four interview-assessed PDS dimensions: defence mechanisms, desire and capacity for closeness, sense of self, and comprehension and appreciation of others' experiences and motivations account for 91.1% of variance of g-PDS, with a combination of either two of these four dimensions already explaining between 81.8 and 91.3%. Regarding self-reports, the dimensions depth and duration of connections, self-perception, object perception and attachment capacity to internal objects predicted 61.3% of the variance of a latent interview-based score, with all investigated self-reported dimensions together adding up to 65.2% variance explanation.

CONCLUSIONS

Taken together, our data suggest that focusing on specific dimensions, such as intimacy and identity, in time-limited settings might be viable in determining PDS efficiently.