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.