1. Department of Gastroenterology and Hepatology Marqués de Valdecilla University Hospital School of Medicine University of Cantabria Cantabria Spain
2. Marqués de Valdecilla Research Institute (IDIVAL) Cantabria Spain
3. Department of Gastroenterology and Hepatology Hospital Universitario Puerta de Hierro, Majadahonda School of Medicine Universidad Autónoma Madrid Madrid Spain
4. Gastroenterology and Hepatology Servicio Medicina Digestiva del Hospital Clinico Universitario de Valencia (HUCV) Valencia Spain
5. Department of Epidemiology Faculty of Health Sciences Rey Juan Carlos University Madrid Spain