Two types of mentalization-based treatment (MBT), day hospital MBT (MBT-DH) and intensive outpatient MBT (MBT-IOP), have been shown to be effective in treating patients with borderline personality disorder (BPD). This study evaluated trajectories of change in a multi-site trial of MBT-DH and MBT-IOP at 36 months after the start of treatment.

All 114 patients (MBT-DH n = 70, MBT-IOP n = 44) from the original multicentre trial were assessed at 24, 30 and 36 months after the start of treatment. The primary outcome was symptom severity measured with the Brief Symptom Inventory. Secondary outcome measures included borderline symptomatology, personality and interpersonal functioning, quality of life and self-harm. Data were analysed using multilevel modelling and the intention-to-treat principle.

Patients in both MBT-DH and MBT-IOP maintained the substantial improvements made during the intensive treatment phase and showed further gains during follow-up. Across both conditions, 83% of patients improved in terms of symptom severity, and 97% improved on borderline symptomatology. No significant differences were found between MBT-DH and MBT-IOP at 36 months after the start of treatment. However, trajectories of change were different. Whereas patients in MBT-DH showed greater improvement during the intensive treatment phase, patients in MBT-IOP showed greater continuing improvement during follow-up.

Patients in both conditions showed similar large improvements over the course of 36 months, despite large differences in treatment intensity. MBT-DH and MBT-IOP were associated with different trajectories of change. Cost-effectiveness considerations and predictors of differential treatment outcome may further inform optimal treatment selection.

Two types of mentalisation-based treatment (MBT) have been developed and empirically evaluated for borderline personality disorder (BPD): day hospital MBT (MBT-DH) and intensive out-patient MBT (MBT-IOP). No trial has yet compared their efficacy.

To compare the efficacy of MBT-DH and MBT-IOP 18 months after start of treatment. MBT-DH was hypothesised to be superior to MBT-IOP because of its higher treatment intensity.

In a multicentre randomised controlled trial (Nederlands Trial Register: NTR2292) conducted at three sites in the Netherlands, patients with BPD 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 6 months from baseline to 18 months after start of treatment. Data were analysed using multilevel modelling based on intention-to-treat principles.

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.

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 receiving MBT-DH and MBT-IOP, thus, seem to follow different trajectories of change, which may have important implications for clinical decision-making. Longer-term follow-up and cost-effectiveness considerations may ultimately determine the optimal intensity of specialised treatments such as MBT for patients with BPD.

Detailed population-based survey information on the relationship between the severity of common mental disorders (CMDs) and treatment for mental health problems is heavily based on North American research. The aim of this study was to replicate and expand existing knowledge by studying CMD severity and its association with treatment contact and treatment intensity in The Netherlands.

Data were obtained from the Netherlands Mental Health Survey and Incidence Study-2 (NEMESIS-2), a nationally representative face-to-face survey of the general population aged 18–64 years (n = 6646, response rate = 65.1%). DSM-IV diagnoses and disorder severity were assessed with the Composite International Diagnostic Interview Version 3.0 (CIDI 3.0). Treatment contact refers to at least one contact for mental health problems made in the general medical care (GMC) or mental health care (MHC) sector. Four levels of treatment intensity were assessed, based on type and duration of therapy received.

Although CMD severity was related to treatment contact, only 39.0% of severe cases received MHC. At the same time, 40.3% of MHC users did not have a 12-month disorder. Increasing levels of treatment intensity ranged from 51.6% to 13.0% in GMC and from 81.4% to 51.1% in MHC. CMD severity was related to treatment intensity in MHC but not in GMC. Sociodemographic characteristics were not significantly related to having experienced the highest level of treatment intensity in MHC.

Mental health treatment in the GMC sector should be improved, especially when policy is aimed at increasing the role of primary care in the management of mental health problems.