Aim: This trial evaluated the efficacy of a CBT smartphone application (ClearlyMe®) for reducing depressive symptoms in adolescents when delivered with and without guidance and when compared to an active control. Design: An online three-arm, parallel-group randomised controlled trial. Ethical approval was provided by the University of New South Wales Human Research Ethics Committee. Methods: Adolescents in Australia aged 12 to 17 years with mild to moderate depressive symptoms as measured by the Patient Health Questionnaire-9 Adolescent version (PHQ-A) who were not receiving treatment or experiencing recent or severe suicidality, had access to a smartphone, and parental consent were randomly allocated to receive (i) self-directed use of ClearlyMe®, (ii) ClearlyMe® with SMS-guided support, or the active control (SMS-delivered psychoeducation content) for six weeks. Participants were not directly informed of their allocation and the statistician was blinded for analysis. Outcomes were assessed at baseline, post intervention (primary endpoint: 6-weeks post baseline) and follow-up (secondary endpoint: 4-months post baseline). Primary outcome was change in depressive symptoms from baseline to post intervention as measured by the PHQ-A. Intention-to-treat analyses used multilevel linear modelling. Results: 569 adolescents (Mean age: 15.89, SD: 1.26, 74.2% female) were included in the analyses. The declines in depressive symptoms post intervention in the self-directed (d=0.35, 95%CI:-0.57 — -0.12) and guided conditions (d=0.33, 95%CI: -.0.55 — -0.10) were significantly greater than the control. The effects of self-directed and guided were comparable. There were no differences between the conditions at follow-up for any outcomes. Secondary outcomes followed a similar pattern of change at both endpoints, although there were no differential effects for anxiety symptoms. The risk of adverse events was almost double in the control when compared to the self-directed (IRR: 1.73, 95%CI: 1.15 — 2.62, P=.009) and guided conditions (IRR: 1.98 (95%CI: 1.27 — 3.08, P=.002). Conclusions: ClearlyMe®, when delivered with or without SMS-guided support, was efficacious for short term reductions in depressive symptoms in adolescents when compared to SMS-delivered psychoeducation. Trial registration: Australian New Zealand Clinical Trials Registry (ACTRN12622000131752). Universal Trial Number: U1111-1271-8519.
