Cluster-randomised hybrid type 2 effectiveness-implementation trial and economic evaluation of a school-based problem-solving intervention for adolescent depression and anxiety: Co-design and trial preparation in Rajasthan, India (360G-Wellcome-340347_Z_25_Z)

Adolescent depression and anxiety are prevalent in India but effective early interventions are scarce. Problem-solving is a common component of evidence- based programmes for both conditions, teaching individuals to identify tractable stressors, generate solutions, and test chosen options. Prior research in New Delhi showed that “Step 1,” a low-cost, school-based problem- solving intervention, reduced mental health symptoms, including internalising difficulties, up to 12-month follow-up. This proposal’s Foundation Phase will adapt Step 1 for secondary schools in Rajasthan, India’s largest state. Intervention materials, supervision and training will be updated for local relevance. We will also co-design a foundational implementation support package, build local partnerships, and finalise a trial protocol to enable rigorous evaluation of experimental implementation strategies. The Impact Phase will test two discrete implementation strategies using a type 2 hybrid effectiveness–implementation trial with a 2×2 factorial design. One comparison will examine the original multi-session programme against a single-session version that has potential to increase efficiency and reach. The other will compare delivery by external lay counsellors versus delivery by existing school staff to assess outcomes across workforce models. Findings will establish scalable, sustainable approaches for delivering Step 1 and inform broader implementation of early mental health interventions across India and beyond.