CASPAR: A Context-Aware Span Refinement Approach for Decision Support

Jing Tao, Amir Eskandari, Farhana Zulkernine


Abstract
This paper presents CASPAR, a two-stage approach for the MedExACT shared task on medical decision span extraction and classification from ICU discharge summaries. Stage 1 performs document-level sequence labeling using a sliding-window RoBERTa encoder with BiGRU and CRF to generate candidate spans. Stage 2 applies a lightweight refinement module that revisits each candidate within its surrounding context to revise category assignments and correct span boundaries. The system achieves a final score of 0.5668 on the official leaderboard, substantially outperforming the organizer baseline on span-level F1. In addition to system description, we provides ablation results, repeated-run validation statistics, and subgroup- and error-level analyses that highlight the challenges of exact boundary recovery and confusion in race categories subgroups in clinical decision extraction.
Anthology ID:
2026.bionlp-2.21
Volume:
Proceedings of the BioNLP 2026 (Shared Tasks)
Month:
July
Year:
2026
Address:
San Diego, California, USA
Editors:
Deepak Gupta, Dina Demner-Fushman
Venues:
BioNLP | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
146–154
Language:
URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.bionlp-2.21/
DOI:
Bibkey:
Cite (ACL):
Jing Tao, Amir Eskandari, and Farhana Zulkernine. 2026. CASPAR: A Context-Aware Span Refinement Approach for Decision Support. In Proceedings of the BioNLP 2026 (Shared Tasks), pages 146–154, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
CASPAR: A Context-Aware Span Refinement Approach for Decision Support (Tao et al., BioNLP 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl-workshops/2026.bionlp-2.21.pdf
Supplementarymaterial:
 2026.bionlp-2.21.SupplementaryMaterial.txt