Evaluating the efficacy and cost-effectiveness of a digital, app-based intervention for depression (VMood) in community-based settings in Vietnam: A stepped-wedge cluster randomized controlled trial

Depression contributes substantially to the global burden of disease, with large treatment gaps, particularly in low- and middle-income countries (LMICs) like Vietnam. Digital mental health interventions (DMHIs) offer a promising solution, yet evidence for the efficacy and cost-effectiveness of digitally delivered adaptations of evidence-based interventions in LMICs remains limited. This trial evaluated the efficacy and cost-effectiveness of VMood, an app-based DMHI for depression adapted from an evidence-based in-person intervention, in Vietnam. We conducted a stepped-wedge cluster randomized controlled trial across 48 communes in eight Vietnamese provinces. A total of 480 adults screening positive for moderate depression (Patient Health Questionnaire-9 score 10-19), with a retention rate of 97.9%. Communes were randomized to immediate access to VMood or to enhanced usual care, consisting of a limited version of the app during the delay period. The primary outcome was depression caseness (PHQ-9 [≥] 10). Analyses followed an intention-to-treat approach using generalized estimating equations. A cost-effectiveness analysis estimated incremental costs per quality-adjusted life-year (QALY) gained. A total of 477 trial participants were included in the primary analysis. VMood was associated with a 59% reduction in the odds of depression at 6 months (adjusted odds ratio 0.41, 95% CI 0.19-0.89). Mean PHQ-9 scores decreased by 1.9 points (95% CI -3.6 to -0.3) at 6 months. Incremental costs were 1.205 million VND ($47 USD) (95% CI: 1.006 million VND, 1.297 million VND) with 0.008 incremental QALYs (95% CI: 0.006, 0.010), resulting in a 99.7% cost-effectiveness probability at a willingness-to-pay threshold of two times GDP/capita. VMood significantly reduced depressive symptoms and was highly likely to be cost-effective. As a scalable, low-cost intervention, VMood may help reduce the depression treatment gap in settings with limited specialist capacity, supporting investment in evidence-based DMHIs within community-based mental health systems. This trial was registered at ClinicalTrials.gov (NCT05783531) on March 8, 2023. Available from: https://clinicaltrials.gov/study/NCT05783531. Author SummaryDepression is a leading cause of disability worldwide, yet access to effective treatment remains limited, particularly in low- and middle-income countries (LMICs). Digital mental health interventions (DMHIs), such as mobile apps, can reduce depressive symptoms, especially when adapted from evidence-based treatments and delivered with human support. However, most evidence comes from high-income countries, with limited data on efficacy and cost-effectiveness in LMICs. VMood is a mobile app adapted from supported self-management, a modified approach to psychotherapy that is grounded in principles of Cognitive Behavioural Therapy and delivered in-person with support from non-specialist providers. The in-person intervention was shown to be effective in the Vietnamese context in a clinical trial. Here, we conducted a stepped-wedge cluster randomized controlled trial across eight provinces in Vietnam to evaluate the efficacy and cost-effectiveness of VMood. Participants received either the VMood app with supportive coaching provided by a social worker, or enhanced usual care, with subsequent access to the VMood app. Over six months, VMood significantly reduced depression caseness compared with the control group. Economic analysis showed that VMood represents good value for money and was feasible to deliver through existing community systems. Findings provide novel and policy-relevant evidence demonstrating that DMHIs can reduce depression and provide good value for money in LMICs.