1. Nutrition and Health Research Center, National Institute of Public Health, Cuernavaca 62100, Mexico
2. Clinical Epidemiology Research Unit & Cochrane Mexico UNAM Center, Hospital Infantil de Mexico Federico Gomez, Mexico City 06720, Mexico
3. Departamento de Ciencias Sociales en Salud, Dirección de Investigaciones Epidemiológica y Psicosociales, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City 14370, Mexico
4. Center for Research in Evaluation and Surveys, National Institute of Public Health, Cuernavaca 62100, Mexico