DP-IPI: A Hybrid Differential Privacy Text Rewriting Mechanism for Indirect Personal Identifiers in Clinical Texts

Ibrahim Baroud, Stephen Meisenbacher, Sebastian Möller, Florian Matthes, Roland Roller


Abstract
Despite the strengths of modern anonymization and de-identification techniques, the risk of re-identification remains significant due to the indirect identifiers remaining in texts. To address this problem, recent works have applied text rewriting under Differential Privacy (DP) to prevent data linkage by perturbing texts via noise addition. Such methods privatize all tokens in a text indiscriminately, diminishing text quality and usability in critical domains such as in clinical settings. Focusing on indirect personal identifiers (IPIs), we introduce a utility-preserving DP text rewriting method that only privatizes spans containing IPIs. We show that our method effectively reduces re-identification risks in clinical texts while being producing more coherent and usable output texts, leading to higher privacy-utility trade-offs. In this, we demonstrate the effectiveness of hybrid text privatization, which leverages the promise of DP in an efficient, usable manner.
Anthology ID:
2026.findings-emnlp.2156
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
46129–46143
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2156/
DOI:
Bibkey:
Cite (ACL):
Ibrahim Baroud, Stephen Meisenbacher, Sebastian Möller, Florian Matthes, and Roland Roller. 2026. DP-IPI: A Hybrid Differential Privacy Text Rewriting Mechanism for Indirect Personal Identifiers in Clinical Texts. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 46129–46143, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
DP-IPI: A Hybrid Differential Privacy Text Rewriting Mechanism for Indirect Personal Identifiers in Clinical Texts (Baroud et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.2156.pdf