用连续时间扩散模型生成混合类型医疗记录,更准更快且保护隐私。
CDMT-EHR: A Continuous-Time Diffusion Framework for Generating Mixed-Type Time-Series Electronic Health Records
- 采用双向门控循环单元建模时间依赖,支持连续时间扩散。
- 统一高斯扩散处理分类变量,实现多特征联合建模,仅需50步采样。
- 自适应噪声调度提升生成质量,适合不平衡临床数据生成。
电子健康记录(EHR)对临床研究至关重要,但隐私问题严重限制数据共享。合成数据生成是潜在解决方案,但EHR包含随时间演变的数值与分类特征,带来独特挑战。现有扩散模型多基于离散时间,存在有限步近似误差且训练与采样步数耦合。本文提出一种用于混合类型时间序列EHR的连续时间扩散框架,贡献包括:(1) 基于双向门控循环单元的连续时间扩散,捕捉时序依赖;(2) 通过可学习的连续嵌入实现分类变量的统一高斯扩散,支持跨特征联合建模;(3) 因子化可学习噪声调度,按特征和时间步动态适应学习难度。在两个大规模重症监护数据集上的实验表明,该方法在下游任务表现、分布保真度和判别性上均优于现有方法,且采样仅需50步(基线需1,000步)。无分类器引导进一步实现了对类别不平衡临床场景的有效条件生成。
原文摘要 · Abstract (English)
Electronic health records (EHRs) are invaluable for clinical research, yet privacy concerns severely restrict data sharing. Synthetic data generation offers a promising solution, but EHRs present unique challenges: they contain both numerical and categorical features that evolve over time. While diffusion models have demonstrated strong performance in EHR synthesis, existing approaches predominantly rely on discrete-time formulations, which suffer from finite-step approximation errors and coupled training-sampling step counts. We propose a continuous-time diffusion framework for generating mixed-type time-series EHRs with three contributions: (1) continuous-time diffusion with a bidirectional gated recurrent unit backbone for capturing temporal dependencies, (2) unified Gaussian diffusion via learnable continuous embeddings for categorical variables, enabling joint cross-feature modeling, and (3) a factorized learnable noise schedule that adapts to per-feature-per-timestep learning difficulties. Experiments on two large-scale intensive care unit datasets demonstrate that our method outperforms existing approaches in downstream task performance, distribution fidelity, and discriminability, while requiring only 50 sampling steps compared to 1,000 for baseline methods. Classifier-free guidance further enables effective conditional generation for class-imbalanced clinical scenarios.
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