1. Department of Public Health and Infectious Diseases, University of Rome Sapienza, Rome, Italy
2. Emergency Medicine Research Group Edinburgh (EMERGE), Department of Emergency Medicine, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh, EH16 4SA, United Kingdom
3. Department of Critical Care, Royal Infirmary of Edinburgh, Little France Crescent, Edinburgh, EH16 4SA, United Kingdom