1. First Propedeutic Department of Internal Medicine, Medical School, Aristotle University of Thessaloniki, AHEPA University Hospital, Thessaloniki, Greece
2. Department of Medicine, Medical School, University of Thessaly, Larissa, Greece
3. Department of Internal Medicine, Medical School, University of Ioannina, University Hospital of Ioannina, Ioannina, Greece
4. Department of Hygiene and Epidemiology, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
5. Department of Internal Medicine, Oslo University Hospital, Oslo, Norway