Background Violence against adolescents is a universal reality, with severe individual and societal costs. There is a critical need for scalable and effective violence prevention strategies such as parenting programmes, particularly in low‑ and middle‑income countries where rates of maltreatment are highest. Digital interventions may be a scalable and cost‑effective alternative to in‑person delivery, yet maximising caregiver engagement is a substantial challenge. This trial employs a cluster randomised factorial experiment and a novel mixed‑methods analytic approach to assess the effectiveness, cost‑effectiveness, and feasibility of intervention components designed to optimise engagement in an open‑source parenting app, ParentApp for Teens. The app is based on the evidence‑based Parenting for Lifelong Health for Teens programme, developed collaboratively by academic institutions in the Global South and North, the WHO, and UNICEF. Methods/design Sixteen neighbourhoods, i.e., clusters, will be randomised to one of eight experimental conditions which consist of any combination of three components (Support: self‑guided/moderated WhatsApp groups; App Design: sequential workshops/non‑sequential modules; Digital Literacy Training: on/off ). The study will be conducted in low‑income communities in Tanzania, targeting socioeconomically vulnerable caregivers of adolescents aged 10 to 17 years (16 clusters, 8 conditions, 640 caregivers, 80 per condition). The primary objective of this trial is to estimate the main effects of the three components on engagement. Secondary objectives are to explore the interactions between components, the effects of the components on caregiver behavioural outcomes, moderators and media‑tors of programme engagement and impact, and the cost‑effectiveness of components. The study will also assess enablers and barriers to engagement qualitatively via interviews with a subset of low, medium, and high engaging participants. We will combine quantitative and qualitative data to develop an optimised ParentApp for Teens delivery package.
Background: Violence and abuse exert extensive health, social, and economic burdens on adolescents in low- and middle-income countries. Digital parenting interventions are promising for mitigating risks at scale. However, their potential for public health impact hinges on meaningful engagement with the digital platform. Objective: The objective of this study was to evaluate the impact of 3 intervention design and implementation factors aimed at increasing engagement with a noncommercialized, offline-first smartphone app for caregivers of adolescents in Tanzania, in partnership with the United Nations Children’s Fund, the World Health Organization, and the Tanzanian national government. Methods: Following Multiphase Optimization Strategy (MOST) principles, we conducted a 2×2×2 cluster randomized factorial trial involving caregivers of adolescents aged 10 to 17 years. Caregivers were recruited by community representatives from 16 urban and periurban communities (ie, clusters) in the Mwanza region of Tanzania. Each cluster was randomized to 1 of 2 levels of each factor: guidance (self-guided or guided via facilitator-moderated WhatsApp groups), app design (structured or unstructured), and preprogram digital support (basic or enhanced). Primary outcomes were automatically tracked measures of engagement (app launches, modules completed, and home practice activities reviewed), with secondary outcomes including modules started, time spent in the app, and positive behaviors logged. Generalized linear mixed-effects models assessed the impact of experimental factors on engagement. Results: Automatically tracked engagement data from 614 caregivers were analyzed, of which 205 (33.4%) were men. Compared to self-guided participants, receiving guidance alongside the app led to significantly more app launches (mean ratio [MR] 2.93, 95% CI 1.84-4.68; P<.001), modules completed (MR 1.29, 95% CI 1.05-1.58; P=.02), modules started (MR 1.20, 95% CI 1.02-1.42; P=.03), time spent in the app (MR 1.45, 95% CI 1.39-1.51; P<.001), and positive behavior logs (MR 2.73, 95% CI 2.07-3.60; P<.001). Compared to the structured design, unstructured design use resulted in significantly more modules completed (MR 1.49, 95% CI 1.26-1.76; P<.001), home practice activity reviews (MR 7.49, 95% CI 5.19-10.82; P<.001), modules started (MR 1.27, 95% CI 1.06-1.52; P=.01), time spent in the app (MR 1.84, 95% CI 1.70-1.99; P<.001), and positive behavior logs (MR 55.68, 95% CI 16.48-188.14; P<.001). While analyses did not detect an effect of enhanced digital support on directly observed engagement, the combination of enhanced digital support and guidance positively influenced engagement across a range of outcomes. Conclusions: This study is the first to systematically optimize engagement with a digital parenting intervention in a low- and middle-income country. Our findings offer important learnings for developing evidence-based, scalable digital interventions in resource-constrained settings. Trial Registration: Pan-African Clinical Trial Registry PACTR202210657553944; https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=24051