Hybrid SMART-MRTs are a type of experimental study design used to construct an optimized Multimodal Adaptive Intervention (MADI). In Hybrid SMART-MRTs, the unit of intervention (e.g., patient), is randomized multiple times across different intervention modalities (e.g., a human-delivered modality and a digital modality). These randomizations help us answer scientific questions about how best to combine services (e.g., treatments) that are sequenced and adapted by different modalities at different time scales.
For example, consider optimizing a MADI that includes a behavioral intervention delivered every 2 weeks by a clinician, coupled with a smartphone (digital) app that is designed to encourage daily engagement in healthy behaviors. A Hybrid SMART-MRT may randomize patients: (i) every two weeks to understand the effect of transitioning to a more intensive behavioral intervention or to stay the course, as well as (ii) every evening to understand the effect of sending a digital prompt to engage in healthy behaviors.