Large Language Models (LLMs) have yielded fast and dramatic progress in NLP, and now offer strong few- and zero-shot capabilities on new tasks, reducing the need for annotation. This is especially exciting for the medical domain, in which supervision is often scant and expensive. At the same time, model predictions are rarely so accurate that they can be trusted blindly. Clinicians therefore tend to favor "interpretable" classifiers over opaque LLMs. For example, risk prediction tools are often linear models defined over manually crafted predictors that must be laboriously extracted from EHRs. We propose CHiLL (Crafting High-Level Latents), which uses LLMs to permit natural language specification of high-level features for linear models via zero-shot feature extraction using expert-composed queries. This approach has the promise to empower physicians to use their domain expertise to craft features which are clinically meaningful for a downstream task of interest, without having to manually extract these from raw EHR (as often done now). We are motivated by a real-world risk prediction task, but as a reproducible proxy, we use MIMIC-III and MIMIC-CXR data and standard predictive tasks (e.g., 30-day readmission) to evaluate our approach. We find that linear models using automatically extracted features are comparably performant to models using reference features, and provide greater interpretability than linear models using "Bag-of-Words" features. We verify that learned feature weights align well with clinical expectations.

本研究提出使用大型语言模型来进行零样本特征提取并为医学性风险预测模型提供高层次的自然语言特征选取方法，通过自动化特征提取，不需要手动从原始电子病历中提取特征，提供与参考特征相媲美的性能，同时提高了模型的可解释性。

CHiLL: 利用大型语言模型从临床笔记中进行零-shot定制可解释特征提取