1. Department of Internal Medicine, Faculty of Medicine, School of Health Sciences, University of Ioannina, 451 10 Ioannina, Greece
2. 1st Propaedeutic Department of Medicine, Laiko General Hospital of Athens, School of Medicine, National and Kapodistrian University of Athens, 157 72 Athens, Greece
3. Department of Hygiene & Epidemiology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 451 10 Ioannina, Greece