Mentalization-based treatment or psychodynamic treatment programmes for patients with borderline personality disorder - the impact of clinical severity.

Objectives: Mentalization-based treatment (MBT), originally designed for patients with borderline personality disorder (BPD), may be particularly indicated for severe conditions. However, there is limited documentation of how increasing severity of personality disorder (PD) effect outcomes of highly specialized treatments. This study aimed to investigate associations between clinical severity and outcomes for patients in MBT as compared to a psychodynamic group-based treatment programme (PDT).

Design: A naturalistic, longitudinal, comparison study.

Methods: The sample included 345 patients with BPD (PDTn = 281, MBTn = 64). The number of diagnosed PDs, PD criteria, and symptom disorders were chosen as baseline indicators of clinical severity. Clinical outcomes (global functioning, symptom distress, interpersonal problems) were repeatedly assessed over three years. Therapists' fidelity to MBT was satisfactory. Linear mixed models were the applied statistics.

Results: In PDT, greater clinical severity was associated with poorer improvement rates. Clinical severity was not associated with significant differences in outcomes for patients in MBT. Differences in outcomes for patients in MBT and PDT increased significantly with higher severity of disorder.

Conclusions: Supporting previous research, this study indicates that clinical benefits associated with MBT also apply for BPD patients with severe conditions. The results also suggest that increasing severity was a challenge in PDT.

Practitioner Points: MBT may be particularly beneficial for severely disordered BPD patients Differences between MBT and PDT were less pronounced in moderately disordered BPD patients.