Linehan 2015a.

Study characteristics
Methods	49‐week trial with 3 arms Standard dialectical behaviour therapy (DBT) Dialectical behaviour therapy ‐ individual, no groups (DBT‐I) Group dialectical behaviour therapy, no individual (DBT‐S) Duration of trial: 49 weeks Country: USA Setting: university clinic and community setting
Participants	Method of recruitment of participants: outreach to healthcare practitioners Sample size: 99 Diagnosis of borderline personality disorder: Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM‐IV) Means of assessment: Structured Clinical Interview for DSM‐IV Axis II Disorders (SCID‐II) and International personality disorder examination (IPDE) Mean age: 30.3 years (range = 18‐60) Sex: 100% female Comorbidity: not stated Inclusion criteria Met criteria for borderline personality disorder on the IPDE and the SCID‐II At least 2 suicide attempts or non‐suicidal self‐injury (NSSI) episodes (act), or both, in the past 5 years At least 1 suicide attempt in the 8‐week period before entering the study At least 1 suicide attempt in the past year Exclusion criteria IQ below 70 Current psychotic or bipolar condition Seizure disorder Required primary treatment for another life threatening disorder (e.g. severe anorexia nervosa)
Interventions	Experimental group Treatment name: DBT Number randomised to group: 33 Duration: 52 weeks Control/comparison group 1 Comparison name: DBT‐I Number randomised to group: 33 Duration: 49 weeks Control/comparison group 2 Comparison name: DBT‐S Number randomised to group: 33 Duration: 50 weeks All groups: Concomitant psychotherapy: not stated Concomitant pharmacotherapy: psychotropic medication allowed Proportions of participants taking standing psychotropic medication during trial observation period: exact proportions unclear, but no between‐group differences in use of psychotropic medications
Outcomes	Primary Self‐harm, in terms of proportion of patients with non‐suicidal self‐injury (NSSI) (count data) Suicide‐related outcomes, assessed by the proportion of patients with suicidal act Secondary Depression, assessed by the Hamilton Depression Rating Scale (HDRS) Attrition, in terms of patients lost after randomisation in each group
Notes	Sample calculation: yes Ethics approval: yes Comments from review authors: none
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “A computerized adaptive randomization procedure (5) matched participants on age, number of suicide attempts, number of NSSI episodes, psychiatric hospitalizations in the past year, and depression severity”. (p 476)
Allocation concealment (selection bias)	Unclear risk	Quote: “The participant coordinator, who was not blinded to the treatment condition, executed the randomization and collected treatment‐related data”. (p 476)
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: “Assessments were conducted before treatment and quarterly during 1 year of treatment and 1 year of follow‐up by blinded independent assessors trained by instrument developers or approved trainers (including K.A.C. and A.M.M.‐G.) and evaluated as reliable for each instrument.” (p 476)
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comment: no information on ITT, but all randomised participants were included in analysis, so ITT was likely used. No imputation methods seem to have been used. 26/99 randomised were lost at follow‐up. No differences in rate of dropouts between arms, no evidence that group differences in missing data biased major outcome variables
Selective reporting (reporting bias)	High risk	Comment: protocol lists 'coping skills' as a secondary outcome. It was not included in study. 'Reasons for living' and depression and anxiety outcome measures were included in the paper. These were not listed in the protocol. Neither were they mentioned in the paper as post hoc analyses
Other bias	High risk	Treatment adherence Comment: treatment adherence differed significantly between 2 out of 3 groups Adherence bias Comment: first author is the developer of Dialectical Behavioural Therapy (DBT), see http://www.linehaninstitute.org/ab out‐Linehan.php Attention bias Quote: “Participants in standard DBT received significantly more individual sessions than those in DBT‐S owing to weekly sessions in standard DBT and as‐needed sessions in DBT‐S. Participants in standard DBT and DBT‐S received more group therapy sessions than those in DBT‐I owing to the optional nature of group therapy in DBT‐I. Participants in standard DBT attended more groups than those in DBT‐S owing to trend‐level differences in treatment retention.” (p 477)