1. Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, University of California, San Diego, La Jolla, California, USA
2. NOVA Medical School, CHRH, NOVA University of Lisbon, Lisbon, Portugal
3. Center for Clinical Epidemiology and Research Unit of Clinical Epidemiology, OUH Odense University Hospital, Odense, Denmark
4. Department of Critical Care Medicine, Hospital de São Francisco Xavier, CHLO, Estrada do Forte do Alto do Duque, Lisbon, Portugal