M Naderi1, S Sabour2,3. 1. Department of Operating Room, School of Paramedical, Kermanshah University of Medical Sciences, Kermanshah, Iran. 2. Department of Clinical Epidemiology, School of Public Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 3. Safety Promotions and Injury Prevention Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.