REGLAT at AbjadMed: Handling Imbalanced Arabic Medical Text Classification via Hierarchical KNN-MLP Architecture

Ahmed Megahed Fetouh, Mohammed Rahmath, Omer Dawood, Mariam Labib, Nsrin Ashraf, Hamada Nayel


Abstract
In this paper, we demonstrate the system submitted to the shared task of medical text classification in Arabic. We proposed a single-model approach based on fine-tuned LLM-based embedding combined with hierarchical classical classifiers, achieving a competitive macro F1-score of 0.46 on the blind test set. We explored various modeling strategies, including tree-based ensembles, LLM, and hierarchical correction for rare classes, highlighting the effectiveness of domain-specific fine-tuning in low-resource settings. The results demonstrate that a single fine-tuned Arabic BERT variant can serve as a strong baseline in extreme imbalance scenarios, outperforming more complex ensembles in simplicity and reproducibility.
Anthology ID:
2026.abjadnlp-1.46
Volume:
Proceedings of the 2nd Workshop on NLP for Languages Using Arabic Script
Month:
March
Year:
2026
Address:
Rabat, Morocco
Venues:
AbjadNLP | WS
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Publisher:
Association for Computational Linguistics
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Pages:
394–397
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URL:
https://aclanthology.org/2026.abjadnlp-1.46/
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Cite (ACL):
Ahmed Megahed Fetouh, Mohammed Rahmath, Omer Dawood, Mariam Labib, Nsrin Ashraf, and Hamada Nayel. 2026. REGLAT at AbjadMed: Handling Imbalanced Arabic Medical Text Classification via Hierarchical KNN-MLP Architecture. In Proceedings of the 2nd Workshop on NLP for Languages Using Arabic Script, pages 394–397, Rabat, Morocco. Association for Computational Linguistics.
Cite (Informal):
REGLAT at AbjadMed: Handling Imbalanced Arabic Medical Text Classification via Hierarchical KNN-MLP Architecture (Fetouh et al., AbjadNLP 2026)
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https://aclanthology.org/2026.abjadnlp-1.46.pdf