Mentalization-based Treatment Versus Bona-fide Treatment for Patients With Borderline Personality Disorder in Germany

Background: Borderline Personality Disorder (BPD) is a serious mental disorder. Mentalization-based treatment (MBT) is one evidence-based treatment for individuals with BPD. Specifically, MBT has been highlighted for its effectiveness in reduction of suicidal and non-suicidal self-injury (NSSI). Yet, randomized-controlled trials (RCT) on MBT in outpatient settings compared with bona fide treatment (BFT) are still scarce and none has been conducted in Germany. The primary objective of this RCT is to investigate whether outpatient MBT is more effective in the reduction of crisis events (incidences of NSSI and suicide attempts) compared with BFT (namely psychodynamic or cognitive-behavioural psychotherapy) in Germany. Secondary, MBT's efficacy will be investigated with regard to cost-effectiveness, general and interpersonal functioning, BPD and general symptom severity, social adjustment, quality of life, reduction in psychotropic medication and therapy retention. Additionally, moderator as well as common and treatment specific mediator variables will be investigated. Study Design/ Study Population/ Methods: Across 5 study sites in Germany, 304 individuals of all genders from age 18 to 65 with a BPD diagnosis and NSSI or suicide attempts in the past will be asked to participate in the study for two years. In the first year, patients will receive either MBT or BFT (psychodynamic or cognitive behavioural psychotherapy) and will take part in continuous scientific assessments. Scientific assessments will continue after therapy completion up to a 12-moth follow up. As primary outcome, crisis events will be assessed via ecological momentary assessment (EMA) four times a week once per month during the first year and once every three months in the second year. Number of crisis events up to 2 years post randomization will be compared between treatment arms using a log-linear regression model following an intention-to-treat approach. Secondary outcomes, such as borderline and g