Background <p>We recently published treatment outcome data of patients with severe Borderline Personality Disorder (BPD) after one year of Dialectical Behavior Therapy (DBT) in Integrated Care Borderline (ICB). ICB provides DBT in the structures of an Assertive Community Treatment (ACT), working with a multi-professional outpatient team located in a psychiatric hospital. It integrates all elements of DBT with psychiatric and social support as well as crisis intervention if necessary. Previous data demonstrated significant improvements in BPD pathology and psychosocial functioning after one year. Since treatment typically took longer than one year, we now present data of the two years follow-up.</p> Findings <p>In a sample of <i>N</i> = 31 patients with severe BPD outcome data after two years were compared to baseline data. Analyses show significant improvements in psychosocial functioning (GAF), BPD symptoms (BSL-23, SCID-II criteria), and other psychiatric symptoms (BSI, PHQ-9, PCL, suicidality), as well as a reduction of hospital days, and an increase in employment after two years of treatment. Effect sizes in most measures were medium to large, except psychiatric comorbidity (small effect) and anxiety (insignificant).</p> Conclusion <p>Effect sizes after two years of ICB-treatment are larger than after one year, indicating an additional benefit of longer treatment duration for severely ill patients with BPD. Results further support the finding that DBT can be successful in outpatient settings and that ICB seems to have additional effects on employment and hospital days. The ICB approach appears to offer a viable framework for multi-professional outpatient DBT-teams.</p> Trial registration <p>Registration number PV4920 - Integrated Care Borderline – Aerztekammer Hamburg, Germany.</p>