Cognitive behavioural therapy (CBT) and eye-movement desensitisation and reprocessing (EMDR) are NICE-recommended evidence-based treatments for post-traumatic stress disorder (PTSD). However, there is less specification of which individuals might find CBT versus EMDR more effective, or whether other factors influence treatment outcomes. This study describes a service evaluation of trauma-focused CBT (CT-PTSD) and EMDR treatment outcomes for PTSD in a London out-patient NHS Talking Therapies (NHS TT) service over 11 years (N=1580). The evaluation was conducted in an adult sample (mean age 37 years), of which 65% were women. The mean number of treatment episodes for PTSD in the service in the sample was 2.39 (SD=1.86), and the mean number of therapy sessions attended was 6.15 (SD=6.43). When using NHS TT recovery criteria, there was no significant difference between PTSD recovery rates in the service for those who received CT-PTSD (40.8%) versus EMDR (43.6%). CT-PTSD was associated with greater reductions in anxious and depressive (but not PTSD-specific) symptoms than EMDR, but this was confounded by the fact that individuals receiving CT-PTSD in the service had higher anxiety and depression scores at start-of-treatment. Older age and non-female gender were associated with higher anxiety and depression scores. PTSD recovery rates were comparable to other NHS TT services. There is no clear indication that either CBT or EMDR is a more effective treatment for PTSD symptoms in the service, although preliminary findings could inform treatment planning regarding differential effects of the treatments on anxious and depressive symptoms. Other clinical implications are discussed.

1. (1) To gain a better understanding of the relative effectiveness of trauma-focused CBT and EMDR for PTSD, as provided in a working NHS TT service.

2. (2) To allow better-informed clinical and treatment pathway planning for individuals with trauma problems in a talking therapies service.

3. (3) To contribute to the wider research literature on effective interventions for trauma within cognitive therapy and NHS frameworks.

The concept of Service Model Fidelity is considered as a parallel process to Treatment Fidelity in evidence-based psychological therapies. NHS Talking Therapies (formerly IAPT) aimed to increase access to an expanded, upskilled workforce on a national scale. This included systematic training, supervision and front-line service delivery, emphasising treatment fidelity to evidence-based interventions. A further feature of NHS Talking Therapies was modernising and restructuring of the health system that housed these trained practitioners. The term ‘service model fidelity’ (Cromarty, 2016) was coined to emphasise service modernisation aspects as a distinct entity. A definition of the latter is included. Examples of service model fidelity and of service model drift, are outlined to distinguish these from therapist drift. This links to past literature recommending changes in traditional mental health service design and emergent evidence from NHS Talking Therapies. The latter examines publicly available data identifying characteristics of service design, which appear to be predictors of enhanced clinical outcome. Challenges in modernising health systems are discussed and conclusions are made highlighting the crucial role of service model when delivering evidence-based therapies. Suggestions for further research into service configuration to improve experiences of service users are considered. This includes ongoing exploration of service design being more than a qualitative feature, and increasingly appearing as a key factor in enhanced clinical outcome.

1. (1) To identify service model fidelity as separate entity to treatment fidelity.

2. (2) To provide a clear definition of service model fidelity.

3. (3) To delineate therapist drift from service drift.

4. (4) To further examine the role of service model in delivering evidence-based interventions.