Dialectical Behavior Therapy vs Schema Therapy for Patients With Borderline Personality Disorder

Importance: Head-to-head comparisons of evidence-based treatments for borderline personality disorder (BPD), including dialectical behavior therapy (DBT) and schema therapy (ST), remain scarce, despite their widely recognized relevance. Objective: To compare the effectiveness of DBT and ST in a multicenter trial among outpatients with BPD. Design, Setting, and Participants: This 3-year multicenter superiority randomized clinical trial (RCT), part of the BOOTS (Borderline Optimal Treatment Selection) project, was conducted between January 2019 and April 2025. The trial was conducted in 9 Dutch outpatient centers among individuals aged 18 to 65 years with BPD. Assessments were administered by assessors blinded to treatment allocation. Interventions: Participants were randomized to DBT or ST via computerized covariate-adaptive randomization accounting for sex and BPD severity. Both treatments were delivered over 2 years in a combined group-individual format. Main Outcomes and Measures: The primary outcome was the rate of change in DSM-5 BPD severity from baseline to 1-year posttreatment follow-up (3 years after baseline), assessed by the Borderline Personality Disorder Severity Index, fifth version (BPDSI-5) total score. Secondary outcomes included DSM-5 BPD criteria, general symptom severity, functioning, quality of life, well-being, sleep problems, and treatment dropout. Results: Of 204 participants (172 female [84.3%]; mean [SD] age, 32.21 [9.57] years), 95 (46.6%) received DBT and 109 (53.4%) received ST. Intention-to-treat analysis revealed no significant difference between DBT and ST in reducing BPD severity (P = .27, r = 0.09), with large improvements in both treatments. At 36-month follow-up, the estimated mean difference was -1.09 on the BPDSI-5 (Cohen d = 0.15; 95% CI, -0.17 to 0.47). No significant differences between treatments were observed on any secondary outcome, with marked improvements over time in both treatments. Dropout did not differ significantly (DBT: 34% at 1 year, 52% at 2 years; ST: 29% at 1 year, 46% at 2 years). Conclusions and Relevance: This multicenter RCT found no significant differences in effectiveness between DBT and ST for outpatients with BPD, with substantial improvements across outcomes. Future research is warranted to assess equivalence and to determine which treatment works best for whom and why. Trial Registration: https://onderzoekmetmensen.nl Identifier: NL-OMON49443.