Lay-Language and Cross-Lingual Disparities in LLM Medical Diagnosis: A Case Study in Rheumatological Skin Conditions

Grayson Hubbell, Yifei Zhang, Saksham Khatwani, Sriram Sankaranarayanan, Indira Sriram, Maria Leonor Pacheco


Abstract
Patients increasingly turn to large language models (LLMs) for medical self-diagnosis in both English and non-English, often in colloquial language. We evaluate LLM diagnostic performance on rheumatological skin conditions across lay descriptions in English, Spanish, Hindi, and Mandarin, collected from native speakers without medical training, and clinical descriptions in English. Lay descriptions substantially reduce diagnostic accuracy relative to clinical ones, and the gap widens further across non-English languages. A diagnostic-focused system prompt narrows the lay-vs-clinical gap but does little to close the cross-language gap. Current LLMs appear to reproduce, and in some settings amplify, communication-driven disparities documented in clinical medicine.
Anthology ID:
2026.aacl-short.50
Volume:
Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 2: Short Papers)
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venues:
AACL | IJCNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
789–806
Language:
URL:
https://aclanthology.org/2026.aacl-short.50/
DOI:
Bibkey:
Cite (ACL):
Grayson Hubbell, Yifei Zhang, Saksham Khatwani, Sriram Sankaranarayanan, Indira Sriram, and Maria Leonor Pacheco. 2026. Lay-Language and Cross-Lingual Disparities in LLM Medical Diagnosis: A Case Study in Rheumatological Skin Conditions. In Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 2: Short Papers), pages 789–806, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
Lay-Language and Cross-Lingual Disparities in LLM Medical Diagnosis: A Case Study in Rheumatological Skin Conditions (Hubbell et al., AACL-IJCNLP 2026)
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https://aclanthology.org/2026.aacl-short.50.pdf