Saeid Safiri1, Erfan Ayubi2,3, Kamyar Mansori4,5. 1. Managerial Epidemiology Research Center, Department of Public Health, School of Nursing and Midwifery, Maragheh University of Medical Sciences, Maragheh, Iran. 2. Department of Epidemiology, School of Public Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 3. Department of Epidemiology & Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. 4. Social Determinants of Health Research Center, Kurdistan University of Medical Sciences, Sanandaj, Iran. kamyarmansori@yahoo.com. 5. Department of Epidemiology, School of Public Health, Iran University of Medical Sciences, Tehran, Iran. kamyarmansori@yahoo.com.