1. Department of General and Digestive Surgery, Hospital Universitario Rey Juan Carlos, 28933 Madrid, Spain
2. Department of Medical Specialties and Public Health, Faculty of Health Sciences, Rey Juan Carlos University, 28933 Madrid, Spain
3. Department of Anesthesiology and Surgical Critical Care, Hospital Universitario La Princesa, 28006 Madrid, Spain
4. Department of Endocrinology and Nutrition, Hospital Universitario de Fuenlabrada, 28942 Madrid, Spain
5. Department of Endocrinology and Nutrition, Hospital Universitario “Lozano Blesa”, 50009 Zaragoza, Spain
6. Department of General and Digestive Surgery, Hospital Clínico San Carlos, 28040 Madrid, Spain
7. Department of Preventive Medicine, Hospital Universitario Fundación Alcorcón, 28922 Madrid, Spain