Kredlow 2017a.

Study characteristics
Methods	4‐6 month trial with 2 arms Cognitive‐behavioural treatment (CBT) Treatment‐as‐usual (TAU) Duration of trial: 4‐6 months Setting: outpatient clinics
Participants	Method of recruitment of participants: orientation meetings at outpatient centers, referral from clinicians Sample size: 27 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) Mean age: 45.7 years (standard deviation = 9.6) Sex: 96% female Comorbidity: major depressive disorder = 67%, bipolar = 33% Inclusion criteria Aged 18 years or older Severe mental illness diagnosis (i.e. DSM‐IV, major depression, bipolar disorder, schizoaffective disorder, or schizophrenia) and current DSM‐IV diagnosis of PTSD Exclusion criteria Psychiatric hospitalisation or suicide attempt in past 3 months Current substance dependence
Interventions	Experimental group Treatment name: CBT Number randomised to group: 15 Duration: 4‐6 months Control/comparison group Comparison name: TAU Number randomised to group: 12 Duration: 4‐6 months Both groups Concomitant psychotherapy: yes, from local community centers Concomitant pharmacotherapy: yes, from local community centers Proportions of participants taking standing psychotropic medication during trial observation period: unclear
Outcomes	Primary: Borderline personality disorder PD severity, assessed by SCID‐II for borderline personality disorder criteria Mental health status, assessed by the Short Form‐12 (SF‐12) Secondary Dissociation and psychotic‐like symptoms, assessed by the Brief Psychiatric Rating Scale (BPRS) Depression, assessed by the Beck Depression Inventory (BDI) Attrition, in terms of patients lost after randomisation in each group
Notes	Sample size calculation: yes Ethics approval: yes Comments from review authors: participants in CBT improved significantly more in PTSD symptoms, depression, and self‐reported physical health. Effects maintained 1‐year post‐treatment We received some additional information from Dr Muser by email on 28 November 2017. He informed us that the trial was not registered, no protocol had been published, and that they did not assess the participants' IQ.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “Randomization was conducted at a central location in the research center by a computer based randomization program with assignments not known in advance by either clinical or research staff.”
Allocation concealment (selection bias)	Low risk	Quote: “Randomization was conducted at a central location in the research center by a computer based randomization program with assignments not known in advance by either clinical or research staff. When a client had completed the baseline assessment and his or her eligibility for the study was confirmed, the interviewer called the research center and a member of the research team obtained the randomized assignment from the computer. The client was informed about the assignment by the project coordinator”.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quotes: “All assessments were conducted by Masters or Ph.D. level trained clinical interviewers who were blind to treatment assignment.”; “No specific instances of blind breaking were noted in the study”.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: “There were no differences between the groups on any demographic, diagnostic, or baseline measures, nor in the rates of follow‐up assessments".
Selective reporting (reporting bias)	Unclear risk	Comment: no protocol was published and so a clear judgement could not be made.
Other bias	High risk	Treatment adherence Quote: “No efforts were made to control or modify any of these services provided to study participants.” Allegiance bias Comment: KT Mueser is on the Committee on Research Agenda of the Association for the Advancement of Behavior Therapy, and the Task Force on Empirically Validated Treatments of the American Psychological Association, Division 12 (www.bu.edu/sargent/files/2013/05/MueserCV.pdf). Attention bias Comment: 12‐16 sessions for EG, no information on length of TAU intervention Vested interest Comment: funded by National Institute of Mental Health