Is social function a good proxy measure of personality disorder?

Personality assessment may be helped by proxy measures.

To examine the assessment of social functioning in relationship to personality disorder.

Secondary analysis of data from three clinical studies, following deliberate self-harm (n = 460), cognitive behaviour therapy for health anxiety (n = 444) and a 30-year follow-up of 200 anxious/depressed patients. Social function and personality were assessed using the Social Functioning Questionnaire (SFQ) and the Personality Assessment Schedule, with its ICD-11 modification. A 5-item short version of the SFQ, the Short Social Functioning Questionnaire (SSFQ), was also developed. The SFQ score in the first two studies (area under curve [AUC] 0.64 and 0.65) partly predicted personality status; in the third study, this achieved close agreement (AUC SFQ 0.85 [95% CI 0.8-0.9]; AUC SSFQ 0.84 [95% CI 0.78-0.89]). In all studies, social function deteriorated linearly with increasing personality pathology. Cut-off points of 4 on the SSFQ and 7 on the SFQ had high sensitivity (SSFQ 82%-90%; SFQ 82%-83%) and acceptable specificity (SSFQ 66%-75%; SFQ 69%-75%) in identifying personality disorder in the third study.

Social functioning recorded in either a 5-item or 8-item self-rating is a useful proxy measure of personality disturbance and may be the core of disorder.