Day hospital versus intensive outpatient mentalization-based treatment: 3-year follow-up of patients treated for borderline personality disorder in a multicentre randomized clinical trial.

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.