Effects of an Internet intervention (Deprexis) on severe depression symptoms: Randomized controlled trial

AbstractBackgroundStudies have shown that certain Internet interventions can help alleviate depression. However, many such interventions contain personal support elements, making it difficult to ascertain whether the program or the support drives the effects. Studies are needed to investigate whether Internet interventions contribute to symptom reduction even when they are delivered without personal support, and even among severely depressed individuals who often receive other forms of treatment.ObjectiveThis randomized controlled trial aimed to examine the effect of an Internet intervention that was deployed without personal support (“Deprexis”) among adults with initially severe depression symptoms.MethodsAdults recruited from a range of sources who had exceeded the threshold for severe depression (PHQ-9≥15) in a pre-screening assessment and met inclusion criteria were randomized (N=163) to the intervention (3months program access; n=78) or care-as-usual/waitlist control (n=85). A diagnostic screening interview was administered by telephone at baseline to all participants. Online assessments were administered at baseline, 3months (post-treatment), and 6months (follow-up). The main outcome was the Patient Health Questionnaire (PHQ-9) between baseline and post-treatment.ResultsEighty-two percent of randomized participants were reached for the post-treatment assessment. Results for the intention-to-treat (ITT) sample showed significant intervention effects on depression reduction between baseline and post-treatment (linear mixed model [MM], F1,155.6=9.00, p<.01, for the time by condition interaction), with a medium between-group effect size, Cohen's d=0.57 (95% CI: 0.22–0.92). Group differences in depression severity at follow-up were marginally significant in the ITT sample, t (119)=1.83, p=0.07, and smaller than at post-treatment (PHQ-9, d=0.33, 95% CI: −0.03–0.69). The number needed to treat (NNT) at post-treatment was 5, with 38% of participants in the intervention group achieving response (at least 50% PHQ-9 symptom change, plus post-treatment score <10), compared to 17% in the control group, p