BACKGROUND: Dialectical Behaviour Therapy (DBT) is a multi-component cognitive behavioural intervention with proven efficacy in treating people with borderline personality disorder symptoms. Establishing benchmarks for DBT intervention with both adults and adolescents is essential for bridging the gap between research and clinical practice, improving teams' performance and procedures.

AIM: This study aimed to establish benchmarks for DBT using the EQ-5D, Borderline Symptoms List (BSL) and Difficulties in Emotion Regulation Scale (DERS) for adults and adolescents.

METHODS: After searching four databases for randomised controlled trials and effectiveness studies that applied standard DBT to people with borderline symptoms, a total of 589 studies were included (after duplicates' removal), of which 16 met our inclusion criteria. A meta-analysis and respective effect-size pooling calculations (Hedges-g) were undertaken, and heterogeneity between studies was assessed with I2 and Q tests. Benchmarks were calculated using pre-post treatment means of the studies through aggregation of adjusted effect sizes and critical values.

RESULTS: DBT aggregated effect sizes per subsample derived from RCTs and effectiveness studies are presented, along with critical values, categorised by age group (adults vs adolescents), mode of DBT treatment (full-programme vs skills-training) and per outcome measure (EQ-5D, BSL and DERS).

CONCLUSIONS: Practitioners from routine clinical practice delivering DBT and researchers can now use these benchmarks to evaluate their teams' performance according to their clients' outcomes, using the EQ-5D, BSL and DERS. Through benchmarking, teams can reflect on their teams' efficiency and determine if their delivery needs adjustment or if it is up to the standards of current empirical studies.