Time to remission from mild to moderate depressive symptoms: One year results from the EVIDENT-study, an RCT of an internet intervention for depression

•Internet interventions are effective in reducing depressive symptoms short-term.•There are only few long-term studies on the subject with inconsistent results.•In this RCT, users of an internet intervention were followed up for twelve months.•Remission rates over this time were higher for those randomized to the intervention.•The effect of this intervention therefore extends beyond the end of its use.

BackgroundInternet interventions are effective in treating depressive symptoms but few studies conducted a long-term follow-up. The aim of this study was to test the effectiveness of an internet intervention in increasing the remission rate over a twelve months period.MethodsA total of 1013 participants with mild to moderate depressive symptoms were randomized to either care as usual alone or a 12-week internet intervention (Deprexis) plus usual care. Self-rated depression severity (PHQ-9) was assessed regularly over twelve months.ResultsRemission rates over time were significantly higher in the intervention group (Cox regression: hazard ratio [HR] 1.31; p = 0.009). The intervention was more effective in the subgroup not taking antidepressant medication (Cox regression: HR 1.88; p < 0.001). PHQ-change from baseline was greater in the intervention group (linear mixed model [LMM]: p < 0.001) with the between-group effect gradually decreasing from d = 0.36 at three months to d = 0.13 at twelve months (LMM: group by time interaction: p < 0.001).ConclusionThis internet intervention can contribute to achieving remission in people with mild to moderate depressive symptoms, especially if they are not on antidepressant medication (Trial Registration: NCT01636752).