Fidelity in the context of adapting a digital intervention for depression from an evidence-based in-person format in...

Digital interventions have emerged as a promising way to better meet growing population mental health needs. Our team developed a digital depression intervention (VMood; smartphone app) in Vietnam. VMood is adapted from an evidence-based in-person intervention (SSM) developed in Canada and uses cognitive behaviour therapy (CBT) principles with remote coaching by non-specialist providers. Fidelity-adaptation is a major tension in implementation science. Fidelity is the degree an intervention is designed and delivered as intended. Conversely, adaptations are sometimes made for specific contexts. This paper aims to identify key elements of fidelity-adaptation - the degree VMood is consistent theoretically with the SSM intervention and practically with implementing digitally in the Vietnamese setting.

This study uses Perez et al.'s modified version of Carroll et al.'s Implementation Fidelity Framework, focusing on Objective 1: Conceptualizing what intervention fidelity means in this specific context (across modes and cultures) and Objective 2: Conducting fidelity testing to identify key elements along the fidelity-adaptation continuum. Ethnographic data from team meetings explored essential components that must remain intact and necessary adaptations. Non-specialist providers and app users from Vietnam tested VMood. Experts familiar with CBT provided theoretical feedback. Interviews or focus groups were conducted with all participants to gain insights into the adaptive intervention. Qualitative data were analyzed using thematic content analysis.

Participants agreed that VMood captures the essential theoretical components from SSM, noting certain elements of SSM (e.g., change in human contact to online) could not be replicated digitally. Participants also presented adaptation suggestions unique for the digital format to strengthen VMood's acceptability, including keeping the app simple by reducing the amount of text; incorporating more dynamic content (e.g., animations) to increase engagement; and including more culturally appropriate scenarios. Finally, key potential moderators to fidelity reported included quality of program delivery and participant responsiveness.

Findings identified intervention specific elements of fidelity-adaptation and showed that VMood retained essential components of SSM while incorporating adaptations to support implementation within the Vietnamese context. With the global increase in digital health services adapted from in-person delivery, understanding how to balance fidelity with necessary adaptations is important both theoretically and practically.