High-Fidelity Longitudinal Patient Simulation Using Real-World Data

๐Ÿ“… 2026-01-24
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๐Ÿค– AI Summary
This work addresses the significant challenge of simulating clinical patient trajectories, which are shaped by complex biological and social factors, thereby hindering advances in personalized medicine and virtual clinical trials. To this end, we leverage over 200 million real-world electronic health records to develop the first large-scale, pre-trained generative simulator capable of modeling the probabilistic distribution of future clinical events, laboratory results, and their temporal dynamics based solely on a patientโ€™s historical data. The generated trajectories exhibit high fidelity to real-world observations, with incidence rates, lab values, and temporal patterns closely matching empirical data. Notably, the observed-to-expected ratios for diverse clinical outcomes consistently approximate 1.0, demonstrating the modelโ€™s effectiveness and potential for high-fidelity patient trajectory simulation.

Technology Category

Cognitive Modeling & Cognitive Systems: Simulating Human BehaviorMultiagent Systems: Agent-Based Simulation and Emergent BehaviorNatural Language Processing: Code Generation / Program Synthesis from Natural Language

Application Category

User Modeling, Personalization and Recommendation: User modeling and simulation for interactive and conversational systemsWeb Mining and Content Analysis: Web data generation and simulationSocial Networks and Social Media: Generative AI / large language models and their impact on social systems
๐Ÿ“ Abstract
Simulation is a powerful tool for exploring uncertainty. Its potential in clinical medicine is transformative and includes personalized treatment planning and virtual clinical trials. However, simulating patient trajectories is challenging because of complex biological and sociocultural influences. Here, we show that real-world clinical records can be leveraged to empirically model patient timelines. We developed a generative simulator model that takes a patient's history as input and synthesizes fine-grained, realistic future trajectories. The model was pretrained on more than 200 million clinical records. It produced high-fidelity future timelines, closely matching event occurrence rates, laboratory test results, and temporal dynamics in real patient future data. It also accurately estimated future event probabilities, with observed-to-expected ratios consistently near 1.0 across diverse outcomes and time horizons. Our results reveal the untapped value of real-world data in electronic health records and introduce a scalable framework for in silico modeling of clinical care.
Problem

Research questions and friction points this paper is trying to address.

patient simulation
real-world data
clinical trajectories
longitudinal modeling
electronic health records
Innovation

Methods, ideas, or system contributions that make the work stand out.

generative simulation
real-world data
patient trajectory modeling
electronic health records
in silico clinical trials
Y
Yu Akagi
Department of Biomedical Informatics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
T
Tomohisa Seki
Department of Healthcare Information Management, The University of Tokyo Hospital, Tokyo, Japan
H
Hiromasa Ito
Department of Healthcare Information Management, The University of Tokyo Hospital, Tokyo, Japan; Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, Mie, Japan
T
Toru Takiguchi
Department of Healthcare Information Management, The University of Tokyo Hospital, Tokyo, Japan; Department of Emergency and Critical Care Medicine, Nippon Medical School, Tokyo, Japan
K
Kazuhiko Ohe
Artificial Intelligence and Digital Twin in Healthcare, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; Graduate School of Health Data Science, Juntendo University, Tokyo, Japan
Y
Yoshimasa Kawazoe
Department of Healthcare Information Management, The University of Tokyo Hospital, Tokyo, Japan; Artificial Intelligence and Digital Twin in Healthcare, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan