Bridging the Version Gap: Multi-version Training Improves ICD Code Prediction, Especially for Rare Codes

Jinghui Liu, Anthony Nguyen


Abstract
Clinical coding maps clinical documentation to standardized medical codes, an essential yet time-consuming administrative task that could benefit from automation. Current models on ICD coding are typically optimized for codes from a specific ICD version. However, in reality, ICD systems evolve continuously, and different versions are adopted across time periods and regions. Moreover, ICD coding suffers from the long-tail problem, and rare code performance can be a bottleneck for developing implementable models. We examine whether it is viable to train version-independent models by combining data annotated in different ICD versions, which may help address these challenges. We add ICD-9 data to the training of a modified label-wise attention model for ICD-10 prediction, and find that despite the version mismatch, adding ICD-9 yields a 27% increase in micro F1 for 18K rare ICD codes compared to training on ICD-10 alone. On 8K frequent ICD-10 codes, the multi-version training also substantially improves macro metrics, with far fewer model parameters.
Anthology ID:
2026.bionlp-1.29
Volume:
BioNLP 2026
Month:
July
Year:
2026
Address:
San Diego, California
Editors:
Dina Demner-Fushman, Sophia Ananiadou, Kirk Roberts, Junichi Tsujii
Venues:
BioNLP | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
372–381
Language:
URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.bionlp-1.29/
DOI:
Bibkey:
Cite (ACL):
Jinghui Liu and Anthony Nguyen. 2026. Bridging the Version Gap: Multi-version Training Improves ICD Code Prediction, Especially for Rare Codes. In BioNLP 2026, pages 372–381, San Diego, California. Association for Computational Linguistics.
Cite (Informal):
Bridging the Version Gap: Multi-version Training Improves ICD Code Prediction, Especially for Rare Codes (Liu & Nguyen, BioNLP 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl-workshops/2026.bionlp-1.29.pdf