Differentially Private De-identification of Dutch Clinical Notes: A Comparative Evaluation
Paper · 2026 · Michele Miranda, Xinlan Yan, Nishant Mishra et al.
Summary
Secondary use of hospital notes requires removing personal information, and manual redaction is slow and expensive. This study is the first to compare three families of automatic de-identification on real Dutch clinical text: NER-based redaction, LLM prompting, and differential privacy (DP) methods that formally bound leakage. The authors use the Dutch ADE corpus of ICU notes and build five pipelines. Three apply one method alone: gliner-multi-v2.1 for NER, zero-shot LLM redaction, and token-level DP via Metric-DP or RANTEXT. Two are hybrids that run NER or an LLM before DP. They measure residual PII and also train MedRoberta.nl on each privatized corpus for two downstream tasks: drug/disorder entity classification and adverse-drug-event relation classification. DP alone severely damages utility. Redacting text first, particularly with an LLM, gives a better privacy–utility balance. LLM redaction alone stays close to the original data on downstream tasks but offers no formal guarantee. For clinical NLP in languages other than English, the results show the cost of DP and suggest that pre-redaction reduces it.
Key points
- Data: The Dutch ADE dataset contains 102 ICU notes (107,110 words). About 0.83% of tokens are PII, covered by 17 placeholder types such as <NAAM> and <ZIEKENHUIS>.
- DP methods and models:
- Metric-DP uses BERTje embeddings with an ANN index.
- RANTEXT uses Dutch GPT-2 (gpt2-small-dutch).
- The LLMs tested were GPT-4o, DeepSeek-R1 8B/70B, LLaMA-3.1 8B and MedGemma 27B. DeepSeek-70B served as the LLM step in the LLM→DP hybrids.
- Redaction F1: MedGemma scored highest (≈0.59) and GPT-4o lowest (≈0.21), mostly because GPT-4o produced 4,848 false positives.
- Downstream results without DP:
- Entity classification (micro F1): 0.91 on original data, 0.97 after LLM redaction, 0.70 after NER.
- Relation classification (macro F1): 0.62 on original data, 0.59 after LLM redaction, 0.29 after NER.
- Downstream results with DP:
- The best entity classification score was ≈0.51, from NER+RANTEXT at ε=512.
- The best relation classification score was 0.33, from LLM+RANTEXT at ε=512.
Institutions
Fields, topics and concepts
📚 Shelves 5The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksInformation Systems · 1,437 worksPsychology · 1,552 worksSocial Psychology · 306 works
Cite
Cite as Michele Miranda, Xinlan Yan, Nishant Mishra, Rachel Murphy, Ameen Abu Hanna, Sébastien Bratières and Iacer Calixto. 2026. Differentially Private De-identification of Dutch Clinical Notes: A Comparative Evaluation. Proceedings of the 8th Workshop on Clinical Natural Language Processing (Clinical NLP) @ LREC 2026.
@inproceedings{miranda2026differentially,
title = {{Differentially Private De-identification of Dutch Clinical Notes: A Comparative Evaluation}},
author = {Michele Miranda, Xinlan Yan, Nishant Mishra, Rachel Murphy, Ameen Abu Hanna, Sébastien Bratières and Iacer Calixto},
booktitle = {Proceedings of the 8th Workshop on Clinical Natural Language Processing (Clinical NLP) @ LREC 2026},
year = {2026},
doi = {10.63317/2xrg7fmndfhy},
url = {https://doi.org/10.63317/2xrg7fmndfhy}
}References
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