1. Graduate School Kosice Institute for Society and Health; Faculty of Medicine; Safarik University; Kosice Slovak Republic
2. Institute of Public Health; Department of Social Medicine; Faculty of Medicine; Safarik University; Kosice Slovak Republic
3. Institute of Mathematics; Faculty of Science; Safarik University; Kosice Slovak Republic
4. Department of Neurology; Faculty of Medicine; Safarik University; Kosice Slovak Republic
5. Department of Community and Occupational Health; University Medical Center Groningen; University of Groningen; Groningen The Netherlands