Day Hospital versus Intensive Outpatient Mentalization-Based Treatment for borderline personality disorder: A multicentre randomized clinical trial

BACKGROUND: Two types of Mentalization-Based Treatment (MBT) have been developed and empirically evaluated for borderline personality disorder (BPD): Day Hospital MBT (MBT-DH) and Intensive Outpatient MBT (MBT-IOP). No trial has yet compared their efficacy. AIMS: To compare the efficacy of MBT-DH and MBT-IOP 18 months after start of treatment. MBT-DH was hypothesized to be superior to MBT-IOP because of its higher treatment intensity. METHOD: In a multicentre randomized controlled trial conducted at three sites in the Netherlands, BPD patients were randomly assigned to MBT-DH (n=70) or MBT-IOP (n=44). The primary outcome was symptom severity (Brief Symptom Inventory). Secondary outcome measures included borderline symptomatology, personality functioning, interpersonal functioning, quality of life and self-harm. Patients were assessed every six months from baseline to 18 months after start of treatment. Data were analysed using multilevel modelling based on intention-to-treat principles. RESULTS: Significant improvements were found on all outcome measures, with moderate to very large effect sizes for both groups. MBT-DH was not superior to MBT-IOP on the primary outcome measure, but MBT-DH showed a clear tendency towards superiority on secondary outcomes. CONCLUSIONS: Although MBT-DH was not superior to MBT-IOP on the primary outcome measure despite its greater treatment intensity, MBT-DH showed a tendency to be more effective on secondary outcomes, particularly in terms of relational functioning. Patients in MBT-DH and MBT-IOP thus seem to follow different trajectories of change, which may have important implications for clinical decisionmaking. Longer-term follow-up and cost-effectiveness considerations may ultimately determine the optimal intensity of specialized treatments such as MBT for BPD patients. DECLARATION OF INTEREST: P.L. and D.B. have been involved in the training and dissemination of MBT