The increasing availability of sensitive textual data has created an urgent need for robust de-identification methods that enable compliant data sharing while preserving downstream utility. This paper presents DeID-Clinic, a multi-layered framework for automated pseudonymization and re-identification risk assessment of clinical free-text data. Our approach integrates domain-adapted transformer models, including BioBERT and ClinicalBERT, into the MASK de-identification framework to improve the detection and masking of protected health information (PHI). Beyond entity recognition, we introduce a novel document-level risk assessment module that quantifies residual re-identification risk using a combination of k-anonymity, l-diversity, t-closeness, contextual similarity, and entity co-occurrence analysis. Experiments conducted on the i2b2 2014 de-identification dataset demonstrate strong performance, achieving macro-level F1 scores above 0.96 for several entity categories, while enabling quantitative prioritization of high-risk documents for further review. Our results highlight the effectiveness of combining neural de-identification with explicit risk modeling, supporting privacy-preserving data sharing in sensitive domains. Although evaluated on clinical text, the proposed framework is generalizable to other privacy-critical domains such as legal and administrative documents, where reliable pseudonymization and risk-aware anonymization are essential.

In high-stakes domains such as healthcare, privacy concerns severely limit the use of real-world training data. Differentially private (DP) synthetic data offers a promising alternative with formal privacy guarantees, but achieving strong utility remains challenging for clinical note generation due to domain specificity and long-form text complexity. We present Term2Note, a method for synthesising full-length clinical notes under strong DP constraints. By structurally separating content and form, Term2Note generates section-wise note content conditioned on medical terms, with terms and notes privatised under separate DP constraints, and applies a DP quality maximiser to improve outputs. Experiments demonstrate that Term2Note produces synthetic notes with statistical properties closely aligned with real clinical notes, and that downstream models trained on these notes achieve performance comparable to those trained on real clinical data. Compared to existing DP text generation baselines, Term2Note substantially improves both fidelity and utility, without relying on label distribution assumptions, highlighting its effectiveness as a practical privacy-preserving alternative to real clinical notes.

Due to the sensitive nature of clinical letters, their use in model training, medical research, and education is limited. This work aims to generate diverse, de-identified, and high-quality synthetic clinical letters to enhance privacy protection. This study explores various pre-trained language models (PLMs) for text masking and generation, employing various masking strategies with a focus on Bio_ClinicalBERT. Both qualitative and quantitative methods are used for evaluation, supplemented by a downstream Named Entity Recognition (NER) task. Our results indicate that encoder-only models outperform encoder-decoder models. General-domain and clinical-domain PLMs exhibit comparable performance when clinical information is preserved. Preserving clinical entities and document structure yields better performance than fine-tuning alone. Masking stopwords enhances text quality, whereas masking nouns or verbs has a negative impact. BERTScore proves to be the most reliable quantitative evaluation metric in our task. Contextual information has minimal impact, indicating that synthetic letters can effectively replace original ones in downstream tasks. Unlike previous studies that focus primarily on reconstructing original letters or training a privacy-detection and substitution model, this project provides a framework for generating diverse clinical letters while embedding privacy detection, enabling sensitive dataset expansion and facilitating the use of real-world clinical data. Our codes and trained models will be publicly available at https://github.com/HECTA-UoM/Synthetic4Health.