Therapist factors in Internet-delivered cognitive behavioural therapy for major depressive disorder

Internet-delivered cognitive behavioural therapy (CBT) can be an effective method for treating major depression, but it often works best when therapist support is provided in the form of e-mail support or telephone calls. The authors investigated whether there were any intraclass correlations within therapists when delivering CBT for major depression via the Internet. They included data from two trials involving 10 therapists treating a total of 103 patients. The results of a nested one-way model in which participants were treated as raters for different therapists indicated that measures pertaining to symptom reductions (Beck Depression Inventory, Montgomery-Asberg Depression Rating Scale-Self Report, and Beck Anxiety Inventory) did not support a clustering of data within therapists. However, the outcome on a secondary measure of life satisfaction (Quality of Life Inventory) yielded a significant intraclass correlation coefficient for therapists (r = .24, p = .001). The authors propose that text-based treatments are less sensitive to therapist effects when it comes to the primary symptom measures, but that treatment effects not directly targeted by the specific treatment program may be more dependent on the way the support is given and by whom (therapist effect). Limitations of the study are discussed.