Intervening to reduce therapist variability and improve patient outcomes in routine NHS psychological therapies services

The psychological therapies literature is dominated by comparisons between psychological treatments. However, therapist effects can account for more outcome variance. The attention of researchers to the phenomenon of therapist effects is increasing but there has been no research considering whether therapist variability can be reduced whilst at the same time also improving patient outcomes. Accordingly, the current thesis is framed as a proof of concept study testing the idea that interventions to support practitioners can be used to both reduce therapist variability in an Improving Access to Psychological Therapies (IAPT) service and also improve outcomes. Outcome data from 126 therapists and 6476 patients, spanning a 4.5-year period, were utilised to compare therapist effects in three different Phases: Baseline (Phase 1), Directive Intervention (Phase 2), and Collaborative Intervention (Phase 3). A core sample of 35 therapists who were constant across the three Phases were the primary focus, with a secondary analysis utilising the full dataset. Significant variables impacting outcomes were controlled for within multilevel models to allow the identification of therapist effects. A therapist effect of 4.9% was present at Phase 1 in the primary dataset, reducing slightly to 4.7% in Phase 2, and dropping to 1.8%, a minimal effect, in Phase 3. There was a significant improvement in patient outcomes on a key clinical service measure (i.e., PHQ-9 reliable improvement rate) across Phases. Results suggest it may be possible to reduce therapist effects and improve or maintain overall clinical outcomes in a service context. If implemented on a larger scale this would provide more consistent patient outcomes in services. It is not possible to determine cause and effect in relation to the moderators of therapist effects (e.g., deliberate practice). However, the results provide encouragement for efforts to reduce therapist variability and achieve more consistent patient outcomes in psychological therapies services.