Siamak Sabour1,2, Hadis Ghajari3. 1. Department of Clinical Epidemiology, School of Health and Safety, Shahid Beheshti University of Medical Sciences, Chamran Highway, Velenjak, Daneshjoo Blvd, Tehran, I.R., Iran. 2. Safety Promotions and Injury Prevention Research Centre, Shahid Beheshti University of Medical Sciences, Tehran, I.R., Iran. 3. Department of Clinical Epidemiology, School of Health and Safety, Shahid Beheshti University of Medical Sciences, Chamran Highway, Velenjak, Daneshjoo Blvd, Tehran, I.R., Iran. h.ghajari@sbmu.ac.ir.