Siamak Sabour1,2, Azin Torabi3, Hadis Ghajari4. 1. Department of Clinical Epidemiology, School of Health and Safety, Shahid Beheshti University of Medical Sciences, Chamran Highway, Daneshjoo Blvd, Velenjak, PC 198353-5511, Islamic Republic of Iran. 2. Safety Promotions and Injury Prevention Research Centre, Shahid Beheshti University of Medical Sciences, Tehran, Islamic Republic of Iran. 3. Department of Public Health, School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Islamic Republic of Iran. 4. Department of Clinical Epidemiology, School of Health and Safety, Shahid Beheshti University of Medical Sciences, Chamran Highway, Daneshjoo Blvd, Velenjak, PC 198353-5511, Islamic Republic of Iran. h.ghajari@sbmu.ac.ir.