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

BACKGROUND: Internet 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.

METHODS: A 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.

RESULTS: Remission 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).

CONCLUSION: This 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).