Registries and databases-A European perspective.

Registries will enable cohort studies to be performed, which are usually considered to be the best quality of observational studies. The quality of data of registries can be increased if is it possible to merge results ('crosstalk') between registries. A prerequisite for that is an agreed uniform core set of data to be collected and uniform definitions on the items to be collected. This paper discusses problems and barriers with existing registries and provides recommendations from an EMA workshop (European Medicines Agency), for core common data sets and how to secure the quality of data collected. The PedNet registry including >2200 children with haemophilia is presented as an example of a registry/cohort study.