Leveraging Distributed Ledger Technology for Patient Opt-Out Management in the Context of the European Health Data Space.

The EHDS Regulation establishes patient opt-out rights for data use, yet current implementations face fragmented registries and limited tamper-proof mechanisms. In this context, opt-out refers to a patient's proactive right to object to the reuse of their health data for purposes beyond direct clinical care. We propose a distributed ledger technology (DLT)-based architecture to enhance opt-out management. Using design research and regulatory analysis of EHDS and TEHDAS, we developed a proof-of-concept leveraging permissioned DLT, smart contracts, and decentralised identifiers for an immutable registry. This architecture aligns with EHDS requirements for tamper-evident audit trails and cross-border verification. This work bridges regulatory mandates with patient-centric governance across the EU.