A mixed methods evaluation of the working alliance in a blended cognitive behavioural therapy intervention for depression in a multinational randomised controlled trial in Europe

The client and therapist working alliance is widely considered as an important predictor of positive outcomes in face-to-face psychological therapies, but little is known about this concept in blended cognitive behavioural therapy (b-CBT) involving a digital programme and face-to-face sessions. My thesis evaluated the working alliance from client and therapist perspectives in b-CBT and when compared to face-to-face cognitive behavioural therapy (CBT) for depression in Europe. My thesis was nested in a clinical trial investigating the effectiveness of different formats of b-CBT compared to usual care, for adults with depression in nine European countries. A mixed methods approach was adopted. Semi-structured interviews qualitatively explored client and therapist experiences of the working alliance in b-CBT in the UK. Secondary analysis of a subset of pooled data evaluated client (n=676) and therapist (n=616) working alliance scores using linear regression models to test the difference between b-CBT versus face-to-face CBT; determine if working alliance scores are associated with depression scores in b-CBT; and if programme system usability scores influence this association in b-CBT 3-months post-randomisation. Client qualitative interviews (n=19) found a new working alliance dimension called ‘digital heuristics’, defined as a digital programmes’ promotion of active engagement, self-discovery, and autonomous problem-solving. Therapist qualitative interviews (n=13) outlined barriers and facilitators to fostering the working alliance in relation to experiences of time in b-CBT, the functionality of the digital programme, ability to tailor b-CBT, and confidence in delivering b-CBT. Quantitative findings showed that working alliance scores were significantly higher in b-CBT compared to face-to-face CBT for client but not therapist scores. In b-CBT, higher client and therapist working alliance scores were associated with improvements in client depression scores, and were influenced by programme usability scores. Collectively my thesis shows that b-CBT may enhance the quality of the working alliance when compared to face-to-face CBT. The digital programme should therefore be considered when assessing the working alliance in b-CBT for depression.