A feasibility and pilot randomised dismantling trial of the efficacy of self-as-context during acceptance and commitment therapy

The comparative clinical utility of the components of the psychological flexibility model of acceptance and commitment therapy (ACT) have not been equally evaluated. This study therefore conducted a feasibility and pilot two-arm dismantling trial by quarantining the self-as-context component. Sixteen participants were randomised to either 8 sessions of protocol-based ACT (Full-ACT) or 8 sessions of protocol-based ACT minus self-as-context (ACT-SAC). Process measures (flexibility and decentring) were taken at start of treatment, end of treatment, and at 6-week follow-up. Clinical outcome measures (functioning, anxiety, and depression) were collected on a session-by-session basis. Randomisation was well tolerated, all measures were completed, both interventions were competently delivered, and one adverse effect occurred in the full-ACT arm. Ten participants attended all 8 sessions creating a dropout rate of 37.50%. Clinical change appeared linear in both treatments and that treatment gains were maintained. Findings suggest that a full trial is possible and sample size calculations and methodological improvements are provided for this.