Selective Prevention of Depression in Workers Using a Smartphone App: Randomized Controlled Trial (Preprint)
Authors: Deady Mark , Collins Daniel A J , Lavender Isobel , Mackinnon Andrew , Glozier Nicholas , Bryant Richard , Christensen Helen , Harvey Samuel B 
Published: January 2023

BACKGROUND

There is increasing evidence that depression can be prevented; however, universal approaches have had limited success. Appropriate targeting of interventions to at-risk populations has been shown to have potential, but how to selectively determine at-risk individuals remains unclear. Workplace stress is a risk factor for depression and a target for intervention, but few interventions exist to prevent depression among workers at risk due to heightened stress.

OBJECTIVE

This trial aimed to evaluate the efficacy of a smartphone-based intervention in reducing the onset of depression and improving related outcomes in workers experiencing at least moderate levels of stress.

METHODS

A randomized controlled trial was conducted with participants who were currently employed and reported no clinically significant depression and at least moderate stress. The intervention group (n=1053) were assigned <i>Anchored</i>, a 30-day self-directed smartphone app-based cognitive behavioral- and mindfulness-based intervention. The attention-control group (n=1031) were assigned a psychoeducation website. Assessment was performed via web-based self-report questionnaires at baseline and at 1-, 3-, and 6-month postbaseline time points. The primary outcome was new depression caseness aggregated over the follow-up period. The secondary outcomes included depressive and anxiety symptoms, stress, well-being, resilience, work performance, work-related burnout, and quality of life. Analyses were conducted within an intention-to-treat framework using mixed modeling.

RESULTS

There was no significant between-group difference in new depression caseness (<i>z</i> score=0.69; <i>P</i>=.49); however, those in the <i>Anchored</i> arm had significantly greater depressive symptom reduction at 1 month (Cohen <i>d</i>=0.02; <i>P</i>=.049) and 6 months (Cohen <i>d</i>=0.08; <i>P</i>=.03). <i>Anchored</i> participants also showed significantly greater reduction in anxiety symptoms at 1 month (Cohen <i>d</i>=0.07<i>; P</i>=.04) and increased work performance at 1 month (Cohen <i>d</i>=0.07; <i>P</i>=.008) and 6 months (Cohen <i>d</i>=0.13; <i>P</i>=.01), compared with controls. Notably, for <i>Anchored</i> participants completing at least two-thirds of the intervention, there was a significantly lower rate of depression onset (1.1%, 95% CI 0.0%-3.7%) compared with controls (9.0%, 95% CI 6.8%-12.3%) at 1 month (<i>z</i> score=4.50; <i>P</i>&lt;.001). Significant small to medium effect sizes for most secondary outcomes were seen in the highly engaged <i>Anchored</i> users compared with controls, with effects maintained at the 6-month follow-up for depressive symptoms, well-being, stress, and quality of life.

CONCLUSIONS

<i>Anchored</i> was associated with a small comparative reduction in depressive symptoms compared with controls, although selective prevention of case-level depression was not observed in the intention-to-treat analysis. When users adequately engaged with the app, significant findings pertaining to depression prevention, overall symptom reduction, and functional improvement were found, compared with controls. There is a need for a greater focus on engagement techniques in future research.

CLINICALTRIAL

Australian New Zealand Clinical Trials Registry (ANZCTR) ACTRN12620000178943; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=378592