Healthcare organisations practicing evidence-based medicine strive to unite their data assets in order to achieve a wider knowledge base for more sophisticated research as well as to provide a matured decision support service for the care givers. The central point of such an integrated system is a data warehouse, to which all participants have access. Due to the high confidentiality of healthcare data, and the privacy policy of participating organisations, the proposed warehouse is not created physically but as a federated system. Its conceptual model is based on a widely accepted international standard to overwhelm the heterogeneity of the components.

Any disclosure of health data, especially when related to a particular person, could be irreparably harmful, and their protection is even legally prescribed. Depersonalisation and pseudonymisation are used to ensure that personal identities are made secret before sending data to the federation.

urance data warehouses (HEWAF) is described. The protection of data privacy and confidentiality in the underlying warehouse is guaranteed through reliable security measures in the federation.