Part of the appeal of digital health interventions, including mHealth, is the potential for greater reach in places where conventional health promotion is hampered by geographical, financial or social barriers. Yet, 'engagement' – typically understood as user experience and interactions with technology - remains a persistent challenge, particularly in places where technology access or familiarity with technology is limited. We undertook an evaluation of a childrearing app to promote socioemotional and cognitive development in early childhood across the world. In this article, we present findings from qualitative research on app rollout in Indonesia, the first of numerous low- and middle-income countries targeted by the app. We draw on systems theory and complexity thinking to broaden the lens of 'engagement' beyond individual users to encompass collective systems (families and communities), exploring how the intervention was harnessed to meet local contextual needs. The qualitative research involved semi-structured interviews, workshops and audio diaries with 57 diverse stakeholders, including Indonesian parents, caregivers, and collaborators involved in funding, development, and dissemination of the app. We observed the importance of social connection, sense-making, and interactive learning for enhancing engagement with the app and its messages. Enthusiastic users, strongly linked across community networks (e.g. kindergarten teachers), improvised dissemination strategies to facilitate uptake. Interactive learning that tapped into familiar social structures (e.g. intergenerational hierarchies) was crucial for engagement. Understanding ways the app failed to tap into structures of social connection served to highlight the need to embed strategies to support collective engagement.

Background: Emerging evidence suggests that positive impacts can be generated when digital health interventions are designed to be responsive to the cultural and socioeconomic context of their intended audiences.

Objective: This narrative review aims to synthesize the literature about the cultural adaptation of digital health interventions. It examines how concepts of culture and context feature in design and development processes, including the methods, models, and content of these interventions, with the aim of helping researchers to make informed decisions about how to approach cultural adaptation in digital health.

Results: The literature demonstrates varying approaches and levels of cultural adaptation across stages of intervention development, involving considerations such as the research ethos orienting researchers, the methodologies and models used, and the resultant content adaptations. In relation to the latter, culturally appropriate and accessible user interface design and translation can be seen as particularly important in shaping the level of adaptation.

Conclusions: Optimizing cultural adaptation involves linking culture with other contextual factors such as economic conditions and social systems to ensure accessibility and the sustained use of digital health interventions. Culturally humble approaches that use the involvement of a broad range of participants, experts, and other stakeholders are demonstrated to spark vital insights for content development, implementation, and evaluation.

Objective: The Thrive by Five app promotes positive interactions between children and parents, extended family, and trusted community members that support optimal socio-emotional and cognitive development in the early years. This article aims to describe the protocol for a prospective mixed-methods multi-site study evaluating Thrive by Five using surveys, interviews, workshops, audio diaries from citizen ethnographers and app usage data.

Methods: The study activities and timelines differ by site, with an extensive longitudinal evaluation being conducted at two sites and a basic evaluation being conducted at five sites. The learnings from the more comprehensive evaluations inform the iterative research and development processes while also ensuring ongoing evaluation of usability, acceptability and effectiveness of the app and its content across varying contexts. The study evaluates: (1) the impact of the Thrive by Five content on caregiver knowledge, behaviours, attitudes and confidence" (2) how the content changes relationships at the familial, community and system level" (3) how cultural and contextual factors influence content engagement and effectiveness and (4) the processes that facilitate or disrupt the success of the implementation and dissemination.

Results: All in-country partners have been identified and data collection has been completed in Indonesia, Malaysia, Afghanistan, Kyrgyzstan, Uzbekistan, Namibia and Cameroon.

Conclusions: Very few digital health solutions have been trialled for usability and effectiveness in diverse cultural contexts. By combining quantitative, qualitative, process and ethnographic methodologies, this innovative study informs the iterative and ongoing optimisation of the cultural and contextual sensitivity of the Thrive by Five content and the processes supporting implementation and dissemination.