1. Faculty of Medicine, University of Colima, Colima, Col, 28040, Mexico
2. Clinical Epidemiology Research Unit, Mexican Institute of Social Security, Colima, Col, 28000, Mexico
3. Health Sciences Division, University of Monterrey, Monterrey, N.L., 66238, Mexico
4. Public Health Research Group, Claustro Universitario, Chihuahua, Chih., 31320, Mexico