Why Do Self-Harm Prediction Models Struggle to Generalise? – Lexical and Semantic Variations in Emergency Department Triage Notes

Liuliu Chen, Mike Conway, Jo Robinson, Vlada Rozova


Abstract
Self-harm presentations to emergency departments (EDs) are strongly associated with higher suicide risk. NLP models have shown strong performance in detecting self-harm from triage notes within single hospitals, yet performance often declines across institutions. To examine potential causes, we compare ED triage notes from two hospitals by analyzing lexical characteristics, highly associated predictive features, and salient topics. Our results reveal variation in lexical expression and feature importance related to self-harm across hospitals, despite consistent core themes such as self-poisoning and self-injury. These documentation differences are associated with reduced cross-site performance. These findings provide insight into how institutional variation affects the identification of self-harm in clinical text and highlight potential methods to improve model generalisability.
Anthology ID:
2026.clpsych-1.31
Volume:
Proceedings of the 10th Workshop on Computational Linguistics and Clinical Psychology (CLPsych 2026)
Month:
July
Year:
2026
Address:
San Diego, California, USA
Editors:
Aya Zirikly, Kfir Bar, Sean MacAvaney, Molly Ireland, Yaakov Ophir, Dana Atzil-Slonim, Vasudha Varadarajan, Steven Bedrick, Bart Desmet
Venues:
CLPsych | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
383–388
Language:
URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.clpsych-1.31/
DOI:
Bibkey:
Cite (ACL):
Liuliu Chen, Mike Conway, Jo Robinson, and Vlada Rozova. 2026. Why Do Self-Harm Prediction Models Struggle to Generalise? – Lexical and Semantic Variations in Emergency Department Triage Notes. In Proceedings of the 10th Workshop on Computational Linguistics and Clinical Psychology (CLPsych 2026), pages 383–388, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
Why Do Self-Harm Prediction Models Struggle to Generalise? – Lexical and Semantic Variations in Emergency Department Triage Notes (Chen et al., CLPsych 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl-workshops/2026.clpsych-1.31.pdf