1. Gastroenterology Department; Agencia Sanitaria Costa del Sol; Málaga; Spain
2. Gastroenterology Department; Hospital de San Pedro de Alcántara; Cáceres; Spain
3. Gastroenterology Department; Hospital Central de Asturias; Oviedo; Spain
4. Gastroenterology Department; Consorci Sanitari de Terassa; Barcelona; Spain
5. Gastroenterology Department; Hospital de Galdakao; Vizcaya; Spain
6. Gastroenterology Department; Hospital de La Princesa and Instituto de Investigación Sanitaria Princesa (IP); Madrid; Spain