Designing and conducting interventional trials with passive-sensing applications on patient-owned smartphones:...

Digital health technologies offer novel avenues to support cancer survivorship, but their evaluation in clinical trials poses specific methodological and technological challenges. This policy brief paper reports key lessons stemming from the experience of the BD4QoL multicenter randomized clinical trial (RCT), in which an apps' ecosystem for monitoring the quality of life of a multinational cohort of head and neck cancer survivors was implemented. The project deployed a digital platform on patients' own smartphones to gather behavioral data and patient-reported outcomes during post-treatment follow-up. Drawing from this experience, we describe challenges encountered during trial execution including device heterogeneity, reliance on third party apps, regulatory concerns and methodological barriers, and propose actionable advice to support the rigorous and sustainable implementation of digital health intervention for the next generation of RWD-guided RCTs. In particular, this paper examines the challenges of conducting a multicenter randomized trial based on passive sensing and a Bring Your Own Device (BYOD) deployment approach.