Effectiveness of a web-based intervention in treating subthreshold depression and in preventing major depression

Abstract

Background: Evidence for the impact of psychological Interventions in the treatment of subthreshold depression (sD) and in the prevention of Major Depressive Disorder (MDD)is conflicting. The aim of the present research was to evaluate the effectiveness of a web-based guided self-help intervention in the treatment of sD and on the onset of MDD. Methods: In two randomized controlled trials, participants with sD were randomly allocated to a guided web-based intervention (n=202) and enhanced usual care (n=204) or to the same intervention with adherence-focused guidance (n=102) and a waitlist control condition (n=102). The primary outcome was time to onset of MDD in the intervention relative to the control group over a 12-month follow-up period using DSM-IV criteria and the reduction in depressive symptom severity as measured by blind diagnostic raters using the Quick Inventory of Depressive Symptomatology at post-treatment. Results: Cox regression analyses controlling for baseline depressive symptom severity suggested the risk of MDD onset was significantly reduced by 41% in the intervention as compared to the control group (HR=.59, 95% CI .42-.82). The number-needed-to-treat to avoid one new MDD case was 5.9 (95% CI 3.9-14.6). The second study revealed a medium between-group effect size of d=0.40 (95%-CI:0.12–0.68) and a NNT of 7 (95%-CI:3.7–41.2) to achieve one additional treatment response. Conclusions: Reducing the incidence of MDD is possible by offering a web-based guided self-help intervention. Web-based self-help interventions with adherence-focused guidance could be an acceptable and effective approach to reduce a range of negative consequences associated with subclinical depression.