1. Department of Biostatistics, Faculty of Health Sciences in Bytom, Medical University of Silesia in Katowice, 40-055 Katowice, Poland
2. Department of Neurology, Institute of Medical Sciences, University of Opole, 45-040 Opole, Poland
3. Department of Neurological Rehabilitation, Upper Silesian Rehabilitation Center “Repty”, 42-604 Tarnowskie Góry, Poland
4. Department of Epidemiology, Faculty of Health Sciences in Bytom, Medical University of Silesia in Katowice, 40-055 Katowice, Poland