1. Gastroenterology Unit; Instituto de Investigación Sanitaria Princesa (IIS-IP) and CIBERehd; Hospital Universitario de La Princesa; Madrid Spain
2. Gastroenterology Unit and CIBERehd; Hospital Clinic de Barcelona; Barcelona Spain
3. Gastroenterology Unit and IMIBIC; Hospital Reina Sofía; Córdoba Spain
4. Gastroenterology Unit; Hospital Clínico San Carlos; Madrid Spain
5. Gastroenterology Unit and CIBERehd; Hospital Universitario Germans Trias i Pujol; Badalona Spain