1. Center for Research on Health and NutritionNational Institute of Public Health Cuernavaca Morelos Mexico
2. CONACYT—Center for Research on Population HealthNational Institute of Public Health Cuernavaca Morelos Mexico
3. Center for Health Systems ResearchNational Institute of Public Health Cuernavaca Morelos Mexico
4. Health DepartmentUniversidad Iberoamericana Mexico City Mexico