Study protocol for a pre-registered randomised open-label trial of ten-session cognitive behaviour therapy (CBT-T) for eating disorders: does stratified augmented treatment lead to better outcomes?

INTRODUCTION: Further improvement of cognitive-behavioural therapy for eating disorders (CBT-ED) is required that can provide better outcomes. Recent work showed that the length of therapy is not critical in improving outcomes. Rather, stratifying the treatment to individual needs is required to produce significant improvements. The current study adopts the approach of evaluating augmentations to ten-session CBT (CBT-T) where initial response to therapy is gradual rather than rapid. 

METHODS AND ANALYSIS: Clients aged 15 years and over presenting to the Flinders University Services for Eating Disorders between January 2025 and June 2028 will be randomised to receive either CBT-T as usual or CBT-T augmented with therapy modules (CBT-TA) matched to obstacles to progress for gradual responders. Rapid response, assessed using the Eating Disorder Examination Questionnaire, is defined as ≥1.13 decrease in global ED psychopathology at session 4. In CBT-TA, the therapist and gradual responder will collaboratively choose at least one of nine augmentations to incorporate into therapy. Rapid responders in this group will be given access to the augmentations for use in their own time. Data for the main intent-to-treat analyses will be collected on five occasions: baseline assessment (T1), immediately preceding session 4 (T2), end of treatment (T3) and 3-month and 6-month follow-up (T4 and T5). The primary outcome is ED psychopathology, and secondary outcomes include behavioural indicators of the ED, impairment caused by the ED, general negative emotion, self-harm and hope. Analyses will be undertaken on an intention-to-treat basis and will include all participants in the group to which they were randomised. 

ETHICS AND DISSEMINATION: Ethics approval was provided by the Social and Behavioural Research Ethics Committee at Flinders University (7992). This trial was prospectively registered with the Australian New Zealand Clinical Trials Registry (ACTRN12624001495516). The findings arising from the study protocol will be reported to participants and presented at scientific conferences and disseminated by publications submitted to peer-reviewed journals. 

TRIAL REGISTRATION NUMBER: Australian New Zealand Clinical Trials Registry (ACTRN12624001495516).