Hospital information system manages patient's hospitalization information across different applications and databases. As statistics are performed with difficulties on these different databases, the university hospital of Lille developed an anesthesia data warehouse. This common structure stores data related to anesthesia procedures and patient hospital stay. In that way, the joint analysis on intervention's events and patient's outcome is possible. However, data quality remains one of the main issues in this kind of project. Indeed, errors in patient identifier result in difficulties to link data between the different sources. This problem will be approached in the next phase of the project.