1. Department of Pediatrics, Escuela de Medicina, Pontificia Universidad Católica de Chile, Chile
2. Endoscopy Unit, Center of Medical Specialties, Red de Salud UC Christus, Chile
3. Department of Public Health, Escuela de Medicina, Pontificia Universidad Católica de Chile, Chile
4. Department of Gastroenterology and Nutrition, Division of Pediatrics, Escuela de Medicina, Pontificia Universidad Católica de Chile, Chile