Electronic health record (EHR) systems contain a wealth of multimodal clinical data including structured data like clinical codes and unstructured data such as clinical notes. However, many existing EHR-focused studies has traditionally either concentrated on an individual modality or merged different modalities in a rather rudimentary fashion. This approach often results in the perception of structured and unstructured data as separate entities, neglecting the inherent synergy between them. Specifically, the two important modalities contain clinically relevant, inextricably linked and complementary health information. A more complete picture of a patient's medical history is captured by the joint analysis of the two modalities of data. Despite the great success of multimodal contrastive learning on vision-language, its potential remains under-explored in the realm of multimodal EHR, particularly in terms of its theoretical understanding. To accommodate the statistical analysis of multimodal EHR data, in this paper, we propose a novel multimodal feature embedding generative model and design a multimodal contrastive loss to obtain the multimodal EHR feature representation. Our theoretical analysis demonstrates the effectiveness of multimodal learning compared to single-modality learning and connects the solution of the loss function to the singular value decomposition of a pointwise mutual information matrix. This connection paves the way for a privacy-preserving algorithm tailored for multimodal EHR feature representation learning. Simulation studies show that the proposed algorithm performs well under a variety of configurations. We further validate the clinical utility of the proposed algorithm in real-world EHR data.

Speaker Biography:Zhou Doudou is an Assistant Professor in the Department of Statistics and Data Science at the National University of Singapore. He earned his bachelor's degree from the University of Science and Technology of China and his Ph.D. from the University of California, Davis. He completed postdoctoral research at the T.H. Chan School of Public Health at Harvard University. His research interests include electronic health records, high-dimensional statistics, transfer learning, and federated learning. His work has been published in journals such as the Journal of the American Statistical Association (J. Am. Stat. Assoc.), Journal of Machine Learning Research (JMLR), IEEE Transactions on Information Theory, Journal of Biomedical Informatics, Bioinformatics, and Biostatistics.