Background
Major depressive disorder (MDD) is highly prevalent [
1,
2] and has an incidence rate that is high relative to the number of prevalent cases [
3]. The global point prevalence is estimated at 4.7% with an annual incidence rate of 3% [
4]. Moreover, MDD is related to poorer quality of life [
5,
6], increased mortality [
7], and substantial economic costs [
8‐
10]. Currently, MDD ranks as the fourth disorder with the highest disease burden and is projected to be the leading cause of premature mortality and disability in high-income countries by 2030 [
11].
The disease burden attributable to MDD might be reduced in two ways. The first approach is to treat existing cases. But despite the availability of effective MDD treatments, such as face-to-face cognitive-behaviour therapy, behavioural activation therapy or problem-solving therapy [
12‐
14] less than half of depressed patients are recognised and treated [
15]. Furthermore, it is estimated that approximately only one third of the disease burden caused by MDD could be averted assuming the hypothetical scenario of 100% coverage and full compliance to evidence-based treatments [
16,
17].
The second approach is reducing the development of new cases, which requires prevention. Preventive interventions might be capable of contributing to a further reduction in disease burden. A recent meta-analysis of 19 randomised controlled trials demonstrated that preventive interventions based on cognitive behaviour or interpersonal therapy were able to reduce the incidence of MDD by 22% [
18]. One of these studies also showed the effectiveness of minimal contact cognitive-behavioural therapy for depression, based on the ‘Coping with Depression’ course [
19].
Selective prevention aimed at high-risk groups and indicated preventive efforts that target individuals who show already detectable signs of MDD but who do not yet meet the diagnostic criteria for the disorder were particularly effective. Universal prevention aimed at the general population regardless of any risk profile showed only small effects.
Indicated prevention has been suggested to be more “efficient” than selective prevention [
20]. “Efficiency” is here defined in terms of “impact”, that is the number of cases that would be prevented if the targeted risk indicator were fully blocked in the population and “effort” reflecting the number needed to be treated to prevent one new case of MDD. From a clinical point of view, indicated prevention is worthwhile for two reasons. First, subthreshold depression is a highly prevalent condition [
21] and the burden posed on people affected and the community is considerable [
22,
23]. Second, subthreshold depression is a risk indicator for MDD, as the incidence rate of MDD is significantly increased in subjects with subthreshold depression compared to those without ranging from .15 in a general population up to .58 in general medical populations and high risk groups [
24].
Despite their effectiveness, currently available indicated preventive face-to-face interventions face some serious limitations. These include (a) difficulties delivering interventions to the community
en masse due to constraints in the workforce and health care resources [
25,
26], (b) limited availability of evidence-based interventions and clinicians in routine practice, especially in rural areas, and (c) low participation rates even if access to those interventions is at little or no costs [
27]. Therefore, new approaches are needed to enhance the impact of indicated preventive interventions.
Using the Internet to provide (guided) self-help interventions may help to overcome some of the limitations of traditional preventive services. Web-based guided self-help strategies have several advantages over face-to-face approaches. These include: (a) interventions are more easily accessible at any time and place, (b) anonymity is assured when patients want to avoid stigmatisation, (c) a greater potential for the integration of acquired skills in daily life due to an emphasis on the participants’ active role in (guided) self-help interventions [
28] (d) participants can work at their own pace and go through materials as often as they want, and (e) elimination of travel time and costs for both participants and clinicians. Finally (f), web-based interventions are easily scalable implying that only a small increase in therapeutic resources is required for reaching a greater proportion of the eligible population using these interventions. Thus, marginal costs per additional user are low due to an economies of scale effect.
Web-based interventions have shown to be well accepted by participants [
29,
30] and to be effective in the acute treatment of MDD [
12] as well as in reducing depressive symptoms both in adults and adolescents [
31,
32]. However, although several web-based interventions are labelled as preventive interventions, i.e. ‘Colour your life’ [
33,
34], to the best of our knowledge, no study has yet investigated the (cost-) effectiveness of an indicated guided self-help web-based preventive intervention on the onset of diagnosed major depressive disorders.
Objective and research questions
The aim of this study is to evaluate whether a newly developed indicated guided self-help web-based intervention (GET.ON Mood Enhancer Prevention) is effective in preventing the onset of major depressive disorder when compared to an online psychoeducation-only control over a 12-months follow-up period. It is expected that depressive symptomatology will be reduced to a greater extend in the intervention group than in the control condition. It is hypothesised that GET.ON Mood Enhancer Prevention is superior in terms of cost-effectiveness, and QALY health gains compared to the psychoeducation-only control.
Discussion
Major depressive disorder is a highly prevalent disorder associated with a considerable loss of quality of life, increased mortality rates, and formidable economic costs. Due to limited accessibility and efficacy, treating existing cases only contributes to a partial reduction of disease burden. Thus, interventions preventing the onset of MDD should be used to complement treatment-focused interventions and further reduce the burden of this debilitating disorder. Available face-to-face preventive interventions face, however, limitations. Novel approaches are needed that go beyond the limits of traditional services. The Internet may attract people who do not participate in face-to-face interventions. Moreover, it potentially provides the opportunity to offer preventive interventions to the community en masse. To our knowledge, this is one of the first randomised controlled trials that examines the (cost-) effectiveness of a web-based intervention on the onset of major depression in subjects with subthreshold depression.
Limitations of this study include the following. Attrition is a common problem in web-based interventions [
82]. However, providing guidance has been shown to reduce attrition rates [
12] and the intensity of support offered in this study is considered to keep drop-out to a minimum. In addition, the psychometric properties of most of the secondary outcome measures used in this trial have not yet been tested in an online environment.
There are several strengths to this study. First, by conducting this trial a significant contribution to the literature is made as to the best of our knowledge no other study has yet been undertaken that investigates the effect on an indicated guided self-help web-based intervention on the incidence of MDD. Second, Semi-Structured Diagnostic Interviews (SCID) will be conducted two times within the 12-month follow-up period to assess the time to onset of depressive episodes. This frequency of assessments allows for a reasonable temporal precision of onset of depressive episodes according to DSM-IV criteria. Third, an economic evaluation will be performed alongside the randomised controlled trial. If shown to be effective, this web-based preventive intervention could be easily disseminated. As a low-threshold intervention, it would be better accepted among the target group. If shown to be cost-effective, GET.ON Mood Enhancer Prevention will be a valuable tool to efficiently reduce the disease burden attributable to MDD at population level.
Competing interests
Professor Berking is minority shareholder of Minddistrict GmbH, which will provide the platform for the web-based intervention.
Authors’ contributions
MB obtained funding for this study. MB, CB, JR, LB, DE, and DL contributed to the development of the GET.ON Mood Enhancer Prevention training. All authors contributed to the study design. FS contributed to the design of the economic evaluation study. CB drafted the manuscript. CB, DE, PC, FS, and MB contributed to the further writing of the manuscript. All authors read and approved the final manuscript.