# Automatic ICD Coding

Automatic ICD coding assigns standardized diagnostic codes to discharge summaries, but sections such as hospital course and discharge diagnosis follow near-identical templates, so pretraining can latch onto document structure instead of patient-specific clinical meaning. SARL-ICD restricts contrastive pretraining to narrative sections such as chief complaint, history of present illness and past medical history, builds positive pairs from Jaccard similarity over ICD codes expanded with their hierarchy ancestors, injects LLM-augmented code descriptions through a lightweight label-text interaction module, and fuses PLM-CA with PLM-ICD through a mixture-of-experts gate. On MIMIC-IV ICD-10 the full system reaches 28.6% macro-F1 and 61.1% micro-F1, against 26.1% and 59.6% for PLM-CA.

Automatic ICD coding assigns standardized diagnostic codes to discharge summaries, but sections such as hospital course and discharge diagnosis follow near-identical templates, so pretraining can latch onto document structure instead of patient-specific clinical meaning. SARL-ICD restricts contrastive pretraining to narrative sections such as chief complaint, history of present illness and past medical history, builds positive pairs from Jaccard similarity over ICD codes expanded with their hierarchy ancestors, injects LLM-augmented code descriptions through a lightweight label-text interaction module, and fuses PLM-CA with PLM-ICD through a mixture-of-experts gate. On MIMIC-IV ICD-10 the full system reaches 28.6% macro-F1 and 61.1% micro-F1, against 26.1% and 59.6% for PLM-CA.