1. Institute of Epidemiology; Faculty of Medicine; University of Belgrade; Belgrade Serbia
2. Clinic of Dermatovenereology; Clinical Center of Serbia; Belgrade Serbia
3. Institute of Medical Statistics and Informatics; Faculty of Medicine; University of Belgrade; Belgrade Serbia
4. Institute of Social Medicine; Faculty of Medicine; University of Belgrade; Belgrade Serbia
5. Department of Dermatovenereology; Faculty of Medicine; University of Belgrade; Belgrade Serbia