The BloG3 project, funded by the German Federal Ministry of Education and Research under grant number 16SV8374, ran from 1 March 2020 to 31 August 2023 and was carried out at the Charité Comprehensive Cancer Center (CUB) of Charité‑Universitätsmedizin Berlin. Its overarching aim was to create a blockchain‑based health‑data management platform that would enable the creation and maintenance of holistic patient health profiles. The platform was designed to aggregate data from disparate health‑information systems, provide patients with autonomous control over their data, and support secure sharing with clinicians, hospitals, and research institutions.
The CUB’s sub‑project focused on requirements at the interface between medicine, patients, and technology, as well as on the legal and ethical prerequisites for a blockchain‑based system. First, a detailed process and requirements analysis mapped out discharge, treatment, and follow‑up workflows and identified existing IT infrastructures, including the hospital information system (KIS). Second, the team developed a comprehensive data‑protection concept, a data‑protection impact assessment, and a Joint Controller Agreement in accordance with Article 26 of the GDPR, in collaboration with a specialist data‑protection law firm. These documents serve as templates for future projects.
A prototype of the BloG3 application was built and tested with 20 patients in the oncology day clinic. User experience was evaluated using the System Usability Scale (SUS), providing quantitative feedback on the interface’s intuitiveness and overall satisfaction. In parallel, a Delphi study involving patient representatives explored potential use cases and data‑sharing options, ensuring that patient perspectives were embedded in the design. The project also produced a threat‑modeling paper that identified security risks and mitigation strategies for a decentralized health‑data application, and a whitepaper outlining the technical architecture and governance model of BloG3.
Technically, the platform demonstrates how blockchain can be leveraged to achieve decentralised data and rights management while preserving data integrity and auditability. The prototype’s integration with the KIS was achieved through rapid adaptation of data‑exchange formats, allowing the system to remain functional even as the COVID‑19 pandemic disrupted routine clinical workflows. The use of a distributed ledger ensures that once data are recorded, they cannot be altered without consensus, thereby enhancing trust among stakeholders. The system also supports fine‑grained access control, enabling patients to grant or revoke permissions for specific data elements to individual clinicians or research groups.
Collaboration with consortium partners was central to the project’s success. The CUB coordinated the technical integration and patient engagement, while other partners contributed expertise in blockchain technology, health‑information exchange standards, and legal compliance. Regular feedback loops between the CUB and partners facilitated the rapid development of practical, everyday‑use concepts for the BloG3 app. The project’s outcomes—technical prototypes, usability data, threat‑modeling analyses, and legal documentation—have been disseminated through peer‑reviewed publications and a publicly available whitepaper, positioning BloG3 as a significant step toward the integration of distributed health data and patient‑controlled access in oncology care.