A Diffusion-Model Subpopulation Digital Twin for Mobile Health Deployment: A Case Study on the HeartSteps Intervention

TL;DR - JITAI-Twins uses conditional time-series diffusion models to simulate target patient subpopulations before mobile-health interventions launch. This could help researchers evaluate personalization algorithms while reducing burdensome or disengaging real-world experimentation.

• Ensures temporal consistency so future interventions cannot influence generated past behavior.
• Combines observational-data pretraining, fine-tuning on prior intervention studies, and expert-guided target-population calibration.
• Evaluated retrospectively across HeartSteps v2–v4 physical-activity intervention deployments.
• Better reproduced temporal and participant-level structure than simpler simulators.