MedRAGChecker: Claim-Level Verification for Biomedical Retrieval-Augmented Generation

Yuelyu Ji, Min Gu Kwak, Hang Zhang, Xizhi Wu, Chenyu Li, Yanshan Wang


Abstract
Biomedical retrieval-augmented generation (RAG) produces long-form answers that mix supported, under-evidenced, and contradicted claims, demanding fine-grained verification. We propose MedRAGChecker, a claim-level diagnostic framework that combines textual natural language inference (NLI) with a biomedical knowledge-graph (KG) compatibility signal. Its asymmetric selective-gating rule preserves the textual prediction for most claims and applies KG adjustment only to confident textual entailments assigned low plausibility by the KG back-end. We distill GPT-4.1 claim decompositions and NLI pseudo-labels into compact student models and evaluate three biomedical generators on PubMedQA, MedQuAD, LiveQA, and MedRedQA. The student-ensemble results show that selective BioPortal gating increases macro-averaged faithfulness from 60.8% to 64.4% and reduces the contradiction rate from 19.9% to 15.0%. On 172 annotations of 86 claims whose decisions change after fusion, agreement with human evidence judgments increases from 63.4% to 69.8%. A comparison with DRKG shows that fusion behavior varies substantially with KG coverage, entity linking, score construction, and calibration; the comparison therefore characterizes back-end effects rather than isolating a causal effect of coverage.
Anthology ID:
2026.findings-emnlp.399
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
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SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
8431–8454
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URL:
https://aclanthology.org/2026.findings-emnlp.399/
DOI:
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Cite (ACL):
Yuelyu Ji, Min Gu Kwak, Hang Zhang, Xizhi Wu, Chenyu Li, and Yanshan Wang. 2026. MedRAGChecker: Claim-Level Verification for Biomedical Retrieval-Augmented Generation. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 8431–8454, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
MedRAGChecker: Claim-Level Verification for Biomedical Retrieval-Augmented Generation (Ji et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.399.pdf