I. Motivation
In traditional drug delivery systems, it was easy to evaluate the effects of drugs in controlled laboratory environments. However, in the case of mobile DTx apps, it becomes challenging to evaluate and improve the efficacy of DTx, because patients use mobile apps to receive micro-interventions in an uncontrolled daily environment [1]. Since typical clinical trials only look at differences in endpoints (e.g., patients’ weight for weight management), it is non-trivial to examine which intervention components of the mobile DTx app were used and how they made the differences in the endpoints. Not surprisingly, such information in practice is essential for DTx improvement.