What is already known on this topic

The available treatments can only moderately reduce the enormous burden of disease associated with depression.1 Prevention of the transition from subthreshold depression to a full-blown disorder is therefore highly needed. Offering accessible and affordable preventive interventions at a large scale, such as web-based interventions, could be an indispensable strategy to reduce the global burden of depression.

Methods of the study

In the study by Buntrock and colleagues, 406 adults with subthreshold depression (Centre for Epidemiological Studies-Depression Scale score ≥16, but no current major depressive disorder (MDD) according to the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, SCID) were randomly assigned between March 2013 and March 2015 to a web-based self-help intervention (n=202) or a web-based psychoeducation programme, the control group (n=204). Randomisation was conducted by an independent researcher. All participants had unrestricted access to usual care (visits to the primary care clinician). The interventions’ content (6 1-hour sessions) was based on behaviour and problem-solving therapy. Participants were in a non-therapeutic way supported by online trainers, who were graduate students supervised by clinical psychologists. The main outcome was time to onset of MDD in the intervention group relative to the control group over a 12-month follow-up period as assessed by the SCID. Trained psychologists administered the SCID by telephone.

What this paper adds

• A web-based guided self-help intervention is capable of preventing, or at least delaying, the onset of a MDD. After 12 months, 55 participants in the intervention group (27%) and 84 participants in the control group (41%) were diagnosed with MDD.

• Buntrock and colleagues used a standardised interview for assessing MDD. Until now, for effective web-based interventions, the incidence data were collected by self-report.2

• The number needed to treat (NNT) to avoid one new case of MDD was 5.9 (95% CI 3.9 to 14.6). This NNT can compete with the NNTs shown in effectiveness studies of depression treatments in case of full-blown disorders.3

Limitations

• It cannot be concluded that the results apply both for first onset and recurrence of depression as there was no assessment of lifetime history of MDD at baseline. Future studies should examine if these web-based guided self-help interventions are effective both for the prevention of a first onset of depression and the prevention of depression relapse.

• Highly educated women were over-represented in the study (73.9% women, 81.9% high education). Missing out on certain groups, such as men and people with lower education, is a very common phenomenon in web-based intervention trials. The results cannot be generalised to other populations of people with subthreshold depression as we do not know if it works for them.

What next in research

• High-quality trials are needed that evaluate the preventive effects of unguided web-based interventions on the onset of MDD.

• More knowledge is needed about successful implementation strategies for web-based preventive interventions and on how to facilitate implementation in daily practice in healthcare organisations.

• Reach of preventive mental health interventions is far from optimal, in part because people suffering from subthreshold depression may not (always) identify with the goal of tackling depression, but more with symptoms such as worrying or a lack of psychological flexibility or a simple quest ‘just to feel better’. A transdiagnostic approach focusing on symptoms preceding or underlying the development of a depressive or anxiety disorder4 and/or a positive psychological approach in the recruitment procedure for people seeking more well-being5 may help reach more and other groups of people.

Do these results change your practices and why?

Yes. Today, there is enough evidence to justify utilising web-based guided self-help interventions based on cognitive–behavioural and problem-solving therapy in routine mental healthcare in order to prevent MDD. For example, general health practitioners can use these interventions for their patients in primary care and social workers can use them in community work and public mental healthcare. Patients can find and use them on the internet as empowering tools. Some caution is needed in the jungle of web-based interventions: always look for evidence-based interventions, if possible with an approved quality assurance seal.