FedEHR-Gen: Federated Synthetic Time-Series EHR Generation via Latent Space Alignment and Distribution-Aware Aggregation
Pith reviewed 2026-06-29 14:26 UTC · model grok-4.3
The pith
A federated two-stage method generates synthetic time-series EHR data across hospitals with quality comparable to centralized training.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
FedEHR-Gen is the first federated framework for synthetic time-series EHR generation. It uses a two-stage paradigm: a federated autoencoder with layer-wise matching aggregation aligns local encoders into a unified global latent space from heterogeneous hospital data, then a federated temporal conditional variational autoencoder is trained on that space with distribution-aware aggregation to support stable generative modeling despite cross-hospital differences. On the eICU and MIMIC-III datasets the resulting synthetic data achieves generation fidelity, downstream utility, and privacy risk levels comparable to centralized training and consistently better than the standard federated baseline.
What carries the argument
Layer-wise matching aggregation that aligns local encoders into a unified global latent space, together with distribution-aware aggregation for the temporal conditional variational autoencoder.
If this is right
- Hospitals can generate and share synthetic time-series records without exchanging raw patient data.
- Downstream clinical prediction tasks can use the synthetic data for augmentation while keeping privacy risk comparable to centralized baselines.
- The approach remains stable under the high dimensionality and sparsity that cause standard federated averaging to collapse.
- Generation quality stays close to what would be obtained if all hospital records were pooled in one place.
Where Pith is reading between the lines
- The same latent-space alignment step could be reused for other federated tasks such as prediction or anomaly detection on EHR streams.
- If the aligned space proves robust, the framework could be tested on additional privacy-sensitive time-series domains such as wearable sensor data.
- Hospitals with very different case mixes might still gain from the method provided the matching step continues to hold.
- Generated data from this process could be examined for whether it reduces selection bias in models trained only on large academic centers.
Load-bearing premise
The layer-wise matching aggregation successfully projects high-dimensional and sparse EHR features from heterogeneous hospitals onto a single semantically consistent latent space that supports stable downstream temporal generative modeling.
What would settle it
An experiment on a new collection of hospitals with greater feature mismatch where the generated synthetic data produces downstream model performance measurably below that of centralized training on the same pooled records would falsify the claim.
Figures
read the original abstract
Synthetic Electronic Health Record (EHR) generation provides a promising avenue for data augmentation and cross-hospital modeling in privacy-constrained healthcare settings. However, most existing EHR generative models are centralized and require pooling data across hospitals, which is often infeasible when real-world data sharing is restricted. While federated EHR generation offers a natural solution, direct federated modeling often collapses or diverges due to the high dimensionality, sparsity, and cross-hospital heterogeneity of EHR data. In this work, we propose FedEHR-Gen, the first federated framework for synthetic time-series EHR generation across distributed hospitals. FedEHR-Gen uses a two-stage learning paradigm. First, we introduce a federated autoencoder that projects high-dimensional and sparse EHR features onto a compact latent space. To ensure semantic consistency across hospitals, we develop a layer-wise matching aggregation mechanism that aligns local encoders into a unified global latent space. Second, operating on this aligned latent space, we train a federated temporal conditional variational autoencoder (TCVAE) with distribution-aware aggregation, enabling stable temporal generative modeling under severe cross-hospital heterogeneity. Extensive experiments on the eICU and MIMIC-III datasets demonstrate that FedEHR-Gen achieves generation fidelity, downstream utility, and privacy risk comparable to centralized training, while consistently outperforming the standard federated baseline.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript proposes FedEHR-Gen, the first federated framework for synthetic time-series EHR generation across distributed hospitals. It employs a two-stage paradigm consisting of a federated autoencoder with layer-wise matching aggregation to align local encoders into a unified latent space, followed by a federated temporal conditional variational autoencoder (TCVAE) using distribution-aware aggregation for stable temporal modeling under heterogeneity. Experiments on the eICU and MIMIC-III datasets are reported to achieve generation fidelity, downstream utility, and privacy risk comparable to centralized training while outperforming standard federated baselines.
Significance. If the experimental claims hold, the work would constitute a meaningful engineering advance in federated generative modeling for privacy-sensitive domains. By addressing the collapse or divergence issues in direct federated EHR modeling through explicit latent alignment and distribution-aware mechanisms, it could enable practical cross-hospital synthetic data sharing and augmentation without raw data exchange, with potential downstream impact on clinical research and model training under regulatory constraints.
major comments (1)
- [§4 (Experiments)] §4 (Experiments): The central claim of comparability to centralized training (and superiority to federated baselines) in fidelity, utility, and privacy is load-bearing, yet the abstract provides no quantitative metrics, error bars, ablation studies, or description of heterogeneity measurement; if the full experimental section does not supply these with statistical rigor across multiple runs and hospital partitions, the results cannot be evaluated.
minor comments (2)
- [§3.1] The description of the layer-wise matching aggregation could benefit from an explicit algorithm box or pseudocode to clarify how semantic consistency is enforced across encoders.
- [§3.2] Notation for the distribution-aware aggregation weights in the TCVAE stage is introduced without a clear reference to how they are computed from local statistics; a short equation or definition would improve readability.
Simulated Author's Rebuttal
We thank the referee for the constructive feedback on the experimental validation. We address the concern point-by-point below.
read point-by-point responses
-
Referee: [§4 (Experiments)] §4 (Experiments): The central claim of comparability to centralized training (and superiority to federated baselines) in fidelity, utility, and privacy is load-bearing, yet the abstract provides no quantitative metrics, error bars, ablation studies, or description of heterogeneity measurement; if the full experimental section does not supply these with statistical rigor across multiple runs and hospital partitions, the results cannot be evaluated.
Authors: We agree that the abstract is high-level and omits specific numbers. Section 4 of the manuscript reports quantitative results with error bars (mean ± std over 5 random seeds) for fidelity (MMD, Wasserstein-1, FID), utility (AUROC/F1 on downstream tasks), and privacy (MIA success rates) on both eICU and MIMIC-III. Ablations isolate the layer-wise matching and distribution-aware aggregation components (Tables 3-5). Heterogeneity is quantified via per-feature KL divergence and EMD across hospital subsets; experiments use 5- and 10-hospital partitions with explicit non-IID splits. All claims are supported by these results. We will revise the abstract to include 2-3 key quantitative highlights for clarity. revision: partial
Circularity Check
No significant circularity identified
full rationale
The paper presents an engineering framework for federated EHR generation consisting of a two-stage process (federated AE with layer-wise matching aggregation followed by federated TCVAE with distribution-aware aggregation). Central claims rest on experimental results for fidelity, utility, and privacy on eICU and MIMIC-III rather than any closed-form derivation or parameter fit that reduces to the inputs by construction. No self-definitional equations, fitted inputs renamed as predictions, or load-bearing self-citations appear in the provided description; the method is externally validated against centralized baselines and standard federated approaches.
Axiom & Free-Parameter Ledger
Reference graph
Works this paper leans on
-
[1]
Durmus Alp Emre Acar, Yue Zhao, Ramon Matas, Matthew Mattina, Paul What- mough, and Venkatesh Saligrama. 2021. Federated Learning Based on Dy- namic Regularization. InInternational Conference on Learning Representations. https://openreview.net/forum?id=B7v4QMR6Z9w
2021
-
[2]
Abdulrahman Al-Dailami, Hulin Kuang, and Jianxin Wang. 2025. FedComDist: Towards Effective Personalized Federated Learning for Patient Outcome Predic- tion Using Multi-Center Electronic Medical Records.IEEE Journal of Biomedical and Health Informatics(2025)
2025
-
[3]
Jun Bai, Yiliao Song, Di Wu, Atul Sajjanhar, Yong Xiang, Wei Zhou, Xiaohui Tao, Yan Li, and Yue Li. 2025. A unified solution to diverse heterogeneities in one-shot federated learning. InProceedings of the 31st ACM SIGKDD Conference on Knowledge Discovery and Data Mining V. 2. 71–82
2025
-
[4]
Dor Bank, Noam Koenigstein, and Raja Giryes. 2023. Autoencoders.Machine learning for data science handbook: data mining and knowledge discovery handbook (2023), 353–374
2023
-
[5]
Xingran Chen, Zhenke Wu, Xu Shi, Hyunghoon Cho, and Bhramar Mukherjee
-
[6]
Journal of the American Medical Informatics Association32, 7 (2025), 1227–1240
Generating synthetic electronic health record data: a methodological scoping review with benchmarking on phenotype data and open-source software. Journal of the American Medical Informatics Association32, 7 (2025), 1227–1240
2025
-
[7]
Edward Choi, Siddharth Biswal, Bradley Malin, Jon Duke, Walter F Stewart, and Jimeng Sun. 2017. Generating multi-label discrete patient records using generative adversarial networks. InMachine learning for healthcare conference. PMLR, 286–305
2017
-
[8]
Trung Kien Dang, Xiang Lan, Jianshu Weng, and Mengling Feng. 2022. Federated learning for electronic health records.ACM Transactions on Intelligent Systems and Technology (TIST)13, 5 (2022), 1–17
2022
-
[9]
Ittai Dayan, Holger R Roth, Aoxiao Zhong, Ahmed Harouni, Amilcare Gentili, Anas Z Abidin, Andrew Liu, Anthony Beardsworth Costa, Bradford J Wood, Chien-Sung Tsai, et al. 2021. Federated learning for predicting clinical outcomes in patients with COVID-19.Nature medicine27, 10 (2021), 1735–1743
2021
-
[10]
Bowen Deng, Chang Xu, Hao Li, Yu-hao Huang, Min Hou, and Jiang Bian. 2025. Tardiff: Target-oriented diffusion guidance for synthetic electronic health record time series generation. InProceedings of the 31st ACM SIGKDD Conference on Knowledge Discovery and Data Mining V. 2. 474–485
2025
-
[11]
Jian-hui Duan, Wenzhong Li, Derun Zou, Ruichen Li, and Sanglu Lu. 2023. Fed- erated learning with data-agnostic distribution fusion. InProceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition. 8074–8083
2023
-
[12]
Rahim Entezari, Hanie Sedghi, Olga Saukh, and Behnam Neyshabur. 2022. The Role of Permutation Invariance in Linear Mode Connectivity of Neural Networks. InInternational Conference on Learning Representations. https://openreview.net/ forum?id=dNigytemkL
2022
-
[13]
Alfonso Esposito, Yasamin Moghbelan, Ivan Zyrianoff, and Marco Di Felice
-
[14]
InIEEE INFOCOM 2025-IEEE Conference on Computer Com- munications Workshops (INFOCOM WKSHPS)
Transfer-Informed Variational Autoencoder for Federated Learning on Imbalanced IoT data. InIEEE INFOCOM 2025-IEEE Conference on Computer Com- munications Workshops (INFOCOM WKSHPS). IEEE, 1–2
2025
-
[15]
Cristóbal Esteban, Stephanie L Hyland, and Gunnar Rätsch. 2017. Real-valued (medical) time series generation with recurrent conditional gans.arXiv preprint arXiv:1706.02633(2017)
work page internal anchor Pith review Pith/arXiv arXiv 2017
-
[16]
European Parliament and Council of the European Union. 2016. General Data Protection Regulation (GDPR). https://eur-lex.europa.eu/eli/reg/2016/679/oj
2016
-
[17]
Government of Ontario. 2004. Personal Health Information Protection Act, 2004 (PHIPA). https://www.ontario.ca/laws/statute/04p03
2004
-
[18]
Song Han, Hongxin Ding, Shuai Zhao, Siqi Ren, Shengke Zeng, Mengqi Xue, and Ruili Wang. 2025. Fed-GAN: Federated Generative Adversarial Network with Privacy-Preserving for Cross-Device Scenarios.IEEE Transactions on Dependable and Secure Computing(2025)
2025
-
[19]
Huan He, William hao, Yuanzhe Xi, Yong Chen, Bradley Malin, and Joyce Ho
-
[20]
InThe Twelfth International Conference on Learning Representations
A Flexible Generative Model for Heterogeneous Tabular EHR with Missing Modality. InThe Twelfth International Conference on Learning Representations. https://openreview.net/forum?id=W2tCmRrj7H
-
[21]
Hui He, Qi Zhang, Kun Yi, Kaize Shi, Zhendong Niu, and Longbing Cao. 2024. Distributional drift adaptation with temporal conditional variational autoencoder for multivariate time series forecasting.IEEE Transactions on Neural Networks and Learning Systems36, 4 (2024), 7287–7301
2024
-
[22]
Charlie Hou, Mei-Yu Wang, Yige Zhu, Daniel Lazar, and Giulia Fanti. 2025. Private federated learning using preference-optimized synthetic data. InForty-second International Conference on Machine Learning
2025
-
[23]
Alistair EW Johnson, Tom J Pollard, Lu Shen, Li-wei H Lehman, Mengling Feng, Mohammad Ghassemi, Benjamin Moody, Peter Szolovits, Leo Anthony Celi, and Roger G Mark. 2016. MIMIC-III, a freely accessible critical care database.Scientific data3, 1 (2016), 1–9
2016
- [24]
-
[25]
Diederik P Kingma and Max Welling. 2013. Auto-encoding variational bayes. arXiv preprint arXiv:1312.6114(2013)
work page internal anchor Pith review Pith/arXiv arXiv 2013
-
[26]
Harold W Kuhn. 1955. The Hungarian method for the assignment problem.Naval research logistics quarterly2, 1-2 (1955), 83–97
1955
-
[27]
Daixun Li, Weiying Xie, Zixuan Wang, Yibing Lu, Yunsong Li, and Leyuan Fang
-
[28]
Feddiff: Diffusion model driven federated learning for multi-modal and multi-clients.IEEE Transactions on Circuits and Systems for Video Technology34, 10 (2024), 10353–10367
2024
-
[29]
Jin Li, Benjamin J Cairns, Jingsong Li, and Tingting Zhu. 2023. Generating syn- thetic mixed-type longitudinal electronic health records for artificial intelligent applications.NPJ digital medicine6, 1 (2023), 98
2023
-
[30]
Qinbin Li, Bingsheng He, and Dawn Song. 2021. Model-contrastive federated learning. InProceedings of the IEEE/CVF conference on computer vision and pattern recognition. 10713–10722
2021
-
[31]
Tian Li, Anit Kumar Sahu, Manzil Zaheer, Maziar Sanjabi, Ameet Talwalkar, and Virginia Smith. 2020. Federated optimization in heterogeneous networks. Proceedings of Machine learning and systems2 (2020), 429–450
2020
-
[32]
Dianbo Liu, Dmitriy Dligach, and Timothy Miller. 2019. Two-stage federated phenotyping and patient representation learning. InProceedings of the conference. Association for Computational Linguistics. Meeting, Vol. 2019. 283
2019
-
[33]
Gaoyang Liu, Chen Wang, Kai Peng, Haojun Huang, Yutong Li, and Wenqing Cheng. 2019. SocInf: Membership inference attacks on social media health data with machine learning.IEEE Transactions on Computational Social Systems6, 5 (2019), 907–921
2019
-
[34]
Scott M Lundberg and Su-In Lee. 2017. A unified approach to interpreting model predictions.Advances in neural information processing systems30 (2017)
2017
-
[35]
Zhuoran Ma, Yang Liu, Yinbin Miao, Guowen Xu, Ximeng Liu, Jianfeng Ma, and Robert H Deng. 2023. Flgan: Gan-based unbiased federated learning under non-iid settings.IEEE Transactions on Knowledge and Data Engineering36, 4 (2023), 1566–1581
2023
-
[36]
Brendan McMahan, Eider Moore, Daniel Ramage, Seth Hampson, and Blaise Aguera y Arcas. 2017. Communication-efficient learning of deep net- works from decentralized data. InArtificial intelligence and statistics. PMLR, 1273–1282
2017
-
[37]
Jiheum Park, Jason Patterson, Jose M Acitores Cortina, Tian Gu, Chin Hur, and Nicholas Tatonetti. 2025. Enhancing EHR-based pancreatic cancer prediction with LLM-derived embeddings.npj Digital Medicine8, 1 (2025), 465
2025
-
[38]
Zihao Peng, Xijun Wang, Shengbo Chen, Hong Rao, Cong Shen, and Jinpeng Jiang. 2025. Federated Learning for Diffusion Models.IEEE Transactions on Cognitive Communications and Networking(2025)
2025
-
[39]
Tom J Pollard, Alistair EW Johnson, Jesse D Raffa, Leo A Celi, Roger G Mark, and Omar Badawi. 2018. The eICU Collaborative Research Database, a freely available multi-center database for critical care research.Scientific data5, 1 (2018), 1–13
2018
-
[40]
Houxing Ren, Jingyuan Wang, and Wayne Xin Zhao. 2022. Generative adversarial networks enhanced pre-training for insufficient electronic health records model- ing. InProceedings of the 28th ACM SIGKDD Conference on Knowledge Discovery and Data Mining. 3810–3818
2022
-
[41]
Fiona Victoria Stanley Jothiraj and Afra Mashhadi. 2024. Phoenix: A federated generative diffusion model. InCompanion Proceedings of the ACM Web Conference
2024
-
[42]
Shengpu Tang, Parmida Davarmanesh, Yanmeng Song, Danai Koutra, Michael W Sjoding, and Jenna Wiens. 2020. Democratizing EHR analyses with FIDDLE: a flexible data-driven preprocessing pipeline for structured clinical data.Journal of the American Medical Informatics Association27, 12 (2020), 1921–1934
2020
-
[43]
Brandon Theodorou, Cao Xiao, and Jimeng Sun. 2023. Synthesize high- dimensional longitudinal electronic health records via hierarchical autoregressive language model.Nature communications14, 1 (2023), 5305
2023
-
[44]
Muhang Tian, Bernie Chen, Allan Guo, Shiyi Jiang, and Anru R Zhang. 2024. Reliable generation of privacy-preserving synthetic electronic health record time series via diffusion models.Journal of the American Medical Informatics Association31, 11 (2024), 2529–2539
2024
-
[45]
Hongyi Wang, Mikhail Yurochkin, Yuekai Sun, Dimitris Papailiopoulos, and Yasaman Khazaeni. 2020. Federated Learning with Matched Averaging. InInter- national Conference on Learning Representations. https://openreview.net/forum? id=BkluqlSFDS
2020
-
[46]
Jialun Wu, Kai He, Rui Mao, Xuequn Shang, and Erik Cambria. 2025. Harness- ing the potential of multimodal EHR data: A comprehensive survey of clinical predictive modeling for intelligent healthcare.Information Fusion(2025), 103283
2025
-
[47]
Zuobin Xiong, Wei Li, and Zhipeng Cai. 2023. Federated generative model on multi-source heterogeneous data in IoT. InProceedings of the AAAI Conference on Artificial Intelligence, Vol. 37. 10537–10545
2023
-
[48]
Xiaogang Xu, Yi Wang, Liwei Wang, Bei Yu, and Jiaya Jia. 2023. Conditional temporal variational autoencoder for action video prediction.International Journal of Computer Vision131, 10 (2023), 2699–2722
2023
-
[49]
Andrew Yale, Saloni Dash, Ritik Dutta, Isabelle Guyon, Adrien Pavao, and Kristin P Bennett. 2020. Generation and evaluation of privacy preserving syn- thetic health data.Neurocomputing416 (2020), 244–255. 9
2020
-
[50]
Jinsung Yoon, Daniel Jarrett, and Mihaela Van der Schaar. 2019. Time-series generative adversarial networks.Advances in neural information processing systems32 (2019)
2019
-
[51]
Jinsung Yoon, Michel Mizrahi, Nahid Farhady Ghalaty, Thomas Jarvinen, Ash- win S Ravi, Peter Brune, Fanyu Kong, Dave Anderson, George Lee, Arie Meir, et al. 2023. EHR-Safe: generating high-fidelity and privacy-preserving synthetic electronic health records.NPJ digital medicine6, 1 (2023), 141
2023
-
[52]
Doudou Zhou, Han Tong, Linshanshan Wang, Suqi Liu, Xin Xiong, Ziming Gan, Romain Griffier, Boris Hejblum, Yun-Chung Liu, Chuan Hong, et al. 2025. Representation learning to advance multi-institutional studies with electronic health record data.arXiv preprint arXiv:2502.08547(2025)
work page internal anchor Pith review Pith/arXiv arXiv 2025
-
[53]
He Zhu, Jun Bai, Na Li, Xiaoxiao Li, Dianbo Liu, David L Buckeridge, and Yue Li
-
[54]
FedWeight: mitigating covariate shift of federated learning on electronic health records data through patients re-weighting.npj Digital Medicine8, 1 (2025), 286. 10 Appendix A Experimental Details A.1 Datasets We conduct experiments on two large-scale, real-world intensive care unit (ICU) EHR datasets, MIMIC-III and eICU, both of which contain longitudina...
2025
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.