Introduction~Good mental health is of high value from an individual, economic and social perspective. Depression is a serious threat to such a good mental health and highly prevalent worldwide. On a yearly basis about 7% of the European population (around 30 million people) suffer from a major depression (MDD) (Wittchen et al., 2011). If we take subclinical forms of depression into account the prevalence rises up to 15%.~Depression is not only highly prevalent; it is marked by disabling emotional and physical symptoms. It has a severe negative impact on mental wellbeing, quality of life and social and work-related functioning of those who suffer from it both on the short and longer term. This impact equals at least conditions such as diabetes mellitus, heart disease and arthritis (Sprangers et al., 2000). Depression is associated with increased morbidity, mortality, health care utilization and health care costs. The World Health Organisation has predicted that depression will be the foremost overall cause of disability by 2030 (Mathers, & Loncar, 2006).~Objective~The main objective of the planned research is to compare the clinical and cost-effectiveness of blended Cognitive Behavioural Therapy (CBT) for adults with major depressive disorder (MDD) with treatment as usual (TAU).~Study design~The study is a two-arm randomised controlled non-inferiority and cost-effectiveness trial. The trial will be conducted in routine mental health care in Poland, and is a part of the bigger project funded by European Commission (Grant Agreement No: 603098). A total of 150 patients with MDD will be assigned to one of two conditions: 1) blended CBT, 2) TAU. Respondents in both conditions will be followed until 12 months after baseline (measures will be taken at baseline, 3 months, 6 months and 12 months).~Study population~A total of 150 patients with MDD will be recruited from routine clinical practice in Poland and will receive either depression treatment as usual or blended CBT depression treatment.~Treatment fidelity~To ensure treatment fidelity it is required that: (1) a detailed treatment manual is available to guide therapists through the treatment, (2) regular meetings are organized between the therapists and the research team to prevent drift, (3) therapists will register the number of sessions, the frequency of the sessions, the main strategies used in each session and the duration of each contact.~Randomization~Randomization will be conducted by an independent researcher who is not involved in the trial. Randomisation will take place at an individual level, stratified by country, after the eligibility and baseline assessment. The independent researcher will create the allocation scheme with a computerised random number generator (Random Allocation Software). The allocation ratio will be 1:1. We will use block randomization with variable block sizes that vary between 8 and 14 allocations per block. Subjects will be randomized into two groups: Internet based blended depression treatment or treatment as usual. All investigators and clinicians will be unknown to the randomization scheme.~Sample size calculation~Sample size calculation is based on the non-inferiority design and calculated for the primary clinical outcome symptoms of depression. 150 patients in Poland will enable us to detect a clinically significant effect size of d=0.24 (Cuijpers et al., 2014).~Statistical Analysis~Multiple imputation will be used to impute missing cost and effect data. Intention-to-treat analyses (ITT) increase the risk of type I errors in non-inferiority (NI) trials and non-intention-to treat analyses are preferred over ITT analyses in NI designs. Therefore, the primary statistical analyses will be per protocol analyses meaning that only those patients that have completed the treatment will be included in the analyses. ITT analyses will be used in sensitivity analyses to increase confidence in the results obtained by including all participants in the analyses independent of whether they have completed the treatment or not. Blended depression treatment is considered no less effective than care-as-usual when the two-sided 95% confidence interval (the range of plausible differences between the two treatments) lies entirely above the standard mean difference of 0.20 which is the non-inferiority margin and the smallest clinically acceptable difference.
Effective, accessible, and affordable depression treatment is of high importance considering the large individual and economic burden of depression. There is ample support for the effectiveness of Internet-based Cognitive Behavioral Therapy (CBT) for depression which is considered a promising alternative to routine depression treatment strategies. Most evidence comes from randomized controlled trials, however, and not from research in routine practice.~The European Comparative Effectiveness Research on Internet-based Depression Treatment (E-COMPARED) in Poland aims to compare the clinical and cost-effectiveness of blended CBT for adults with major depressive disorder (MDD) with treatment as usual (TAU). The trial will be conducted in routine mental health care in Poland, and is a part of the bigger project funded by European Commission (Grant Agreement No: 603098). In this randomized controlled trial, a total of 150 patients with MDD will be assigned to one of two conditions: 1) blended CBT, 2) TAU. Respondents in both conditions will be followed until 12 months after baseline (measures will be taken at baseline, 3 months, 6 months and 12 months).