Methods	Design: parallel randomised controlled trial
Participants	Participants: community living adults with personality disorder Sex: (for AsPD subgroup; see note 1) 18 male; 6 female Age: (for AsPD subgroup; see note 1) mean 34.4 (SD 8.4) years Unit of allocation: individual participant Number randomised: (for AsPD subgroup) 24 (13 intervention, 11 control) Number completing: not reported; used Last Observation Carried Forward (LOCF) Setting: outpatient; 5 sites; urban and rural; UK (East Midlands) Inclusion criteria: presence of at least one personality disorder (DSM-IV; IPDE); age 18 to 65 years; literacy and cognitive functioning sufficient to allow engagement with the intervention; able to provide written informed consent Exclusion criteria: major functional psychosis Ethnicity: no information on ethnicity reported for AsPD subgroup Baseline characteristics: (for the entire sample including non-AsPD participants) 49/176 (27.8%) visited Accident and Emergency (A + E) for any reason in the previous 6 months; 25/176 (14.2%) visited A + E due to self-harm in the previous 6 months; 21/176 (11.9%) psychiatric hospital admission in the previous 6 months; mean number of contacts with a psychiatrist/month in the last 6 months 0.21 (intervention) and 0.27 (control group); mean number of contacts with other mental health staff/month in the last 6 months 0.63 (intervention) and 0.83 (control group) (for the AsPD subgroup; see note 1) 4/24 (16.7%) AsPD as the only personality disorder; 20/24 (83.3%) AsPD comorbid with at least one other personality disorder
Interventions	Two conditions: brief individual psychoeducation plus problem-solving group sessions/treatment as usual Brief individual psychoeducation plus problem-solving group sessions (n = 13 randomised) TAU whilst on waiting list (n = 11 randomised) Details of conditions: participants in the intervention condition attended an individual psychoeducation programme where they learned about personality disorder and nature of own personality disorder diagnosis. This followed by 16 weekly group-based problem-solving sessions (lasting approximately 2 hours) based on the ’Stop and Think!’ method. Each group was facilitated by 2 facilitators, experienced in working with patients with personality disorder. Groups started with no more than 8 participants in each and were single gender. In TAU, participants were placed on a waiting list Duration of intervention: mean 24 (range 21 to 28) weeks Duration of trial: mean 24 (range 21 to 28) weeks Length of follow up: none
Outcomes	Primary outcomes Social functioning: scores on Social Functioning Questionnaire (SFQ) Secondary outcomes Anger: scores on State-Trait Anger Expression Inventory-2 (STAXI-2) Impulsivity: scores on Barrett Impulsivity Scale (BIS) Other outcomes Social problem-solving ability: mean scores on the Social Problem Solving Inventory -Revised (SPSI-R) Shame: mean scores on the Experience of Shame Scale (ESS) Dissociation: mean scores on the Dissociative Experiences Scale (DES)
Notes	1. 24 (13.6%) of all 176 participants in the sample had AsPD. Of these 13 were allocated to intervention and 11 to control conditions. Data from this AsPD subgroup supplied by trial investigators
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	Research investigators describe a block randomisation procedure using computer-generated random numbers provided by an independent statistician. Review authors judge this adequate to minimise bias
Allocation concealment?	Yes	Allocation codes pre-sealed into identical, sequentially numbered, opaque envelopes that were opened in sequence by research staff with trial coordinator masked to allocations. Review authors consider it unlikely that participants or any investigator enrolling participants could foresee assignment
Blinding? of participants	Unclear	In a study such as this full blinding is difficult to achieve because participants would be aware whether or not they were participating in a psychological intervention and may also be aware of the nature of this intervention. The review authors judged that it would thus not be possible to fully blind participants in this type of study. We found no indication of any specific additional measures taken to reduce the risk of bias that might result from differential behaviours by participants
Blinding? of personnel	Unclear	In a study such as this full blinding is difficult to achieve because personnel would be aware whether or not they were participating in a psychological intervention and may also be aware of the nature of this intervention. The review authors judged that it would thus not be possible to fully blind personnel in this type of study
Blinding? of outcome assessors	Unclear	Outcome measures were self-report questionnaires completed by participants who were not blind to their own allocation status and were scored by research assistants who could have been aware of this allocation status in some cases. In view of this uncertainty, review authors consider a judgement of ’unclear’ to be appropriate as some possibility of bias remains
Incomplete outcome data addressed? All outcomes	Yes	Data from the AsPD subgroup supplied by trial investigators indicate that at the end of the trial 4 of 13 (30.8%) were missing from the intervention condition and 3 of 11 (27.3%) were missing from the TAU condition (all outcomes). Reasons for missing data (and any differences in the reasons between conditions) are not available. Feedback from trial investigators confirmed that missing data occurred where clients declined to complete endpoint questionnaires. Although no further information is available on why these clients declined to participate in this task, review authors considered the reasons for missing data were reasonably likely to be balanced across the treatment conditions
Free of selective reporting?	Yes	Review authors judge that the published report includes all expected outcomes, including those that were pre-specified
Free of other bias?	Unclear	Trial investigators note that outcomes were based on measurements at just two time points (baseline and endpoint) so may be open to bias from those participants in either very optimistic or pessimistic state of mind. They also note that 20 of 24 (83. 3%) participants had at least one other personality disorder. There is also the possibility of bias arising from baseline imbalance in that those in the intervention group were significantly more likely to have had psychiatric hospitalisation at some time in their life in comparison with the controls (although they were not significantly more likely to have been hospitalised in the previous 6 months)