Although few in number, health registries do exist in Spain including information on rare diseases. Areas have been identified by topic lacking registries and also information systems or registries unidentified in the sources used. Continuing efforts must be made to improve the information available on rare diseases.

Since the eighties, health sentinel networks have been active in our country, but with a variety of objectives, methods and different development levels in the autonomous communities. The necessity of standardising the management and harmonising the indicators has concluded in a research project on the Spanish health sentinel networks, one of whose objectives is to establish a guide for work principles and methods. A panel of 23 experts has made a study using the Delphi method to agree, in three consecutive phases, a definition of sentinel network, the objectives and the management principles and other aspects related to the organisation and functioning. Altogether, 41 questions were gathered from a previous draft which needed 80% of consensus in the first phase and 70% in the second. All the experts participated in the first phase, 22 in the second and 20 in the third. A consensus was achieved on 36 questions in the first phase and in 4 of the remaining ones in the second. In the third phase the shape of the guide document was given. The Delphi consensus method has been extremely useful in the resolution of discrepancies and divergences. The experts who were selected outside of the sentinel networks contributed with a wider vision on the objectives and applicability of the health sentinel networks in Spain.