Brief Individual Psychological Intervention for People with Probable Personality Disorder: A Multicentre, Randomised Controlled Superiority Trial

Background: Long-term psychological treatments are recommended for people with personality disorder. Brief interventions are increasingly delivered but of uncertain benefit. We investigated the effectiveness of a brief individual psychological intervention for people with probable personality disorder over a 12-month period.

Methods: The Structured Psychological Support (SPS) study was a multi-centre, researcher-masked, randomised controlled superiority trial, conducted in seven mental health Trusts in England. Participants were 18 years or older, excluding those who: did not consent; had a co-existing psychosis; or were already receiving psychological treatment. We randomised participants to up to 10 sessions of SPS or enhanced treatment as usual (allocation ratio 1∙15: 1), using an independent remote system. The primary outcome was social functioning over 12 months. Data were analysed using multilevel mixed effects general linear regression on an intention-to-treat basis. The trial was prospectively registered (ISRCTN13918289).

Outcomes: Between 7th February 2023 and 31st January 2024, 569 people were screened. Of these, 336 were allocated to the active arm (180) or control arm (156) of the trial, including 257 (75%) women. Mean age was 35 (range = 18 to 68), and 281 (77%) were white. The attrition rate was 15% at 12 months. There was no difference between groups on the primary outcome (Coefficient = 0∙12, 95% CI = -2∙1, 2∙4, p = 0∙91). The probability that SPS is cost effective was between 34-39%. There were 36 serious adverse events affecting 17 participants in the active and 16 in the control arm of the trial. None were judged related to study procedures.

Interpretation: We found no difference in social functioning over one-year among people offered brief psychological intervention and no evidence of cost-effectiveness. These data highlight the importance of improving access to longer-term evidence-based psychological treatment programmes for people with personality disorder.Funding National Institute for Health and Care Research.