Multimethod investigation of interpersonal functioning in borderline personality disorder.

Even though interpersonal functioning is of great clinical importance for patients with borderline personality disorder (BPD), the comparative validity of different assessment methods for interpersonal dysfunction has not yet been tested. This study examined multiple methods of assessing interpersonal functioning, including self- and other- reports, clinical ratings, electronic diaries, and social cognitions in three groups of psychiatric patients (N = 138): patients with (1) BPD, (2) another personality disorder, and (3) Axis I psychopathology only. Using dominance analysis, we examined the predictive validity of each method in detecting changes in symptom distress and social functioning 6 months later. Across multiple methods, the BPD group often reported higher interpersonal dysfunction scores compared with other groups. Predictive validity results demonstrated that self-report and electronic diary ratings were the most important predictors of distress and social functioning. Our findings suggest that self-report scores and electronic diary ratings have high clinical utility, because these methods appear most sensitive to change.