Immediate and long-term effectiveness of adding an Internet intervention for depression to routine outpatient psychotherapy: Subgroup analysis of the EVIDENT trial

Objective: To examine immediate and long-term effectiveness of an adjunctive Internet intervention for depression in a large sample of patients undergoing routine psychotherapy. Method: The current study evaluated a subgroup of patients from the Evident trial, a randomized investigation of a 12-week minimally guided Internet intervention (Deprexis) for the treatment of mild to moderate depression. 340 adults (mean age = 43.3 years; 71.7 % female) of the original sample received routine outpatient psychotherapy during the trial period, resulting in a standard psychotherapy group (n = 174) and an augmented therapy group (n = 166). Outcomes were assessed at baseline, post-treatment and 6-month follow-up. Results: Intention-to-treat analyses indicated that combined treatment led to a greater reduction in symptoms of depression (effect size d = 0.32; p = .002), improved therapeutic progress (d = 0.36; p = .003), and higher mental health-related quality of life (d = 0.34; p = .004). There was no intervention effect on physical health-related quality of life. The same pattern was found at 6-month follow-up, and adjunctive treatment also resulted in increased rates of clinical improvement. Treatment success was independent from therapeutic orientation of combined face-to-face therapy. Conclusion: Results indicate that the adjunctive use of the investigated intervention can produce additional and lasting effects in routine outpatient psychotherapy for mild to moderate levels of depression. The study adds to the ongoing evidence on augmented effects of blended treatment. Future studies should investigate different types of blends in diverse populations by means of change-sensitive assessment strategies.