[A registry of registries and cohorts: recommendations for metadata and policies].

Registries and cohort studies play a central role in patient-oriented medical research, in particular in health services research. In order to increase the transparency about ongoing registries and cohort studies in Germany, and to promote communication and cooperation between the drivers in the field a so-called register portal should be established. Metadata are characteristics that are used to describe registries and cohort studies in the register portal. A limited set of characteristics, the core set, should correctly describe the projects on the one hand while reducing workload for data capture and data administration on the other hand. The core set consists of 26 data elements that had been defined in a Delphi-consensus process involving experts from the working group registries of the German Network for Health Services Research (DNVF) and the working group IT infrastructure and quality management of the Technology, Methods, and Infrastructure for Networked Medical Research (TMF). Transparent policies are required to guarantee traceability and reliability of the portal's services. Six so-called top-level-tasks and 37 use cases were defined in an interim report so far. The metadata have been agreed upon by most of the member associations of the DNVF. Metadata and rules of procedures are the starting point for the practical implementation of the register portal in the next future. © Georg Thieme Verlag KG Stuttgart · New York.