1. Clinical Research Unit, Hospital de Especialidades Centro Médico La Raza, IMSS, Mexico City, México
2. Department of Pathology, Hospital de Especialidades Centro Médico La Raza, IMSS, México City, México
3. Medical Student, Universidad Autónoma de Nayarit, Tepic, México
4. Department of Internal Medicine, Hospital de Especialidades Centro Médico La Raza, IMSS, México City, México; Universidad Nacional Autónoma de México, México City, México
5. Universidad Nacional Autónoma de México, México City, México; Direction of Education and Research, Hospital de Especialidades Centro Médico La Raza, IMSS, México City, México