通过自我反思迭代增强医学问答的可靠性,减少幻觉。
Self-MedRAG: a Self-Reflective Hybrid Retrieval-Augmented Generation Framework for Reliable Medical Question Answering
- 融合稀疏与稠密检索,用递归排序提升证据覆盖
- 自反思模块检测推理依据不足,自动重提问题
- 在MedQA和PubMedQA上准确率分别提升至83.33%和79.82%
大型语言模型在医学问答中展现巨大潜力,但仍易产生幻觉和无根据推理,限制其在临床场景中的可靠性。尽管检索增强生成(RAG)通过引入外部知识缓解此问题,但传统单次检索难以应对需多步推理的复杂生物医学问题。为此,我们提出Self-MedRAG,一种自反思混合检索增强生成框架,模拟临床推理的迭代假设-验证过程。该框架结合稀疏(BM25)与稠密(Contriever)检索器,通过递归排序融合(RRF)最大化证据覆盖,并利用生成器输出带理由的答案,由轻量级自反思模块基于自然语言推理(NLI)或大模型验证其合理性。若理由证据不足,系统将自主重构查询并迭代优化上下文。我们在MedQA和PubMedQA基准上评估了该方法。结果表明,混合检索显著优于单一检索基线;加入自反思环后,MedQA准确率从80.00%提升至83.33%,PubMedQA从69.10%提升至79.82%。这些发现证实,将混合检索与迭代、基于证据的自反思结合,能有效减少无支持陈述,提升基于LLM系统的临床可靠性。
原文摘要 · Abstract (English)
Large Language Models (LLMs) have demonstrated significant potential in medical Question Answering (QA), yet they remain prone to hallucinations and ungrounded reasoning, limiting their reliability in high-stakes clinical scenarios. While Retrieval-Augmented Generation (RAG) mitigates these issues by incorporating external knowledge, conventional single-shot retrieval often fails to resolve complex biomedical queries requiring multi-step inference. To address this, we propose Self-MedRAG, a self-reflective hybrid framework designed to mimic the iterative hypothesis-verification process of clinical reasoning. Self-MedRAG integrates a hybrid retrieval strategy, combining sparse (BM25) and dense (Contriever) retrievers via Reciprocal Rank Fusion (RRF) to maximize evidence coverage. It employs a generator to produce answers with supporting rationales, which are then assessed by a lightweight self-reflection module using Natural Language Inference (NLI) or LLM-based verification. If the rationale lacks sufficient evidentiary support, the system autonomously reformulates the query and iterates to refine the context. We evaluated Self-MedRAG on the MedQA and PubMedQA benchmarks. The results demonstrate that our hybrid retrieval approach significantly outperforms single-retriever baselines. Furthermore, the inclusion of the self-reflective loop yielded substantial gains, increasing accuracy on MedQA from 80.00% to 83.33% and on PubMedQA from 69.10% to 79.82%. These findings confirm that integrating hybrid retrieval with iterative, evidence-based self-reflection effectively reduces unsupported claims and enhances the clinical reliability of LLM-based systems.
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