Blended CBT versus face-to-face CBT: a randomised non-inferiority trial

Background: Internet based cognitive behavioural therapy (iCBT) has been demonstrated to be cost-and clinically effective. There is a need, however, for increased therapist contact for some patient groups. Combining iCBT with traditional face-to-face (ftf) consultations in a blended format (B-CBT) may produce a new treatment format with multiple benefits from both traditional CBT and iCBT such as individual adaptation, lower costs than traditional therapy, wide geographical and temporal availability, and possibly lower threshold to implementation. The primary aim of the present study is to compare directly the clinical effectiveness of B-CBT with face-to-face CBT for adult major depressive disorder. Methods/Design: The study is designed as a two arm randomised controlled non-inferiority trial comparing blended CBT for adult depression with treatment as usual (TAU). In the blended condition six sessions of ftf CBT is alternated with six to eight online modules (NoDep). TAU is defined as 12 sessions of ftf CBT. The primary outcome is symptomatic change of depressive symptoms on the patient-health questionnaire (PHQ-9). Additionally, the study will include an economic evaluation. All participants must be 18 years of age or older and meet the diagnostic criteria for major depressive disorder according to the Diagnostic and Statistical Manual of Mental disorders 4th edition. Participants are randomised on an individual level by a researcher not involved in the project. The primary outcome is analysed by regressing the three-month follow-up PHQ-9 data on the baseline PHQ-9 score and a treatment group indicator using ancova. A sample size of 130 in two balanced groups will yield a power of at least 80% to detect standardised mean differences above 0.5 on a normally distributed variable. Discussion: This study design will compare B-CBT and ftf CBT in a concise and direct manner with only a minimal of the variance explained by differences in therapeutic content. On the other hand, while situated in routine care, ecological validity is somewhat compromised by the controlled manner in which the study is conducted.