1. Intensive Care Unit and
2. Biostatistics Unit, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore;
3. FAST and Chronic Programmes, Alexandra Hospital, National University Health System, Singapore, Singapore;
4. Division of Respiratory & Critical Care Medicine, Department of Medicine, National University Hospital, National University Health System, Singapore, Singapore;
5. Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore; and
6. Medical Affairs, Alexandra Hospital, Singapore, Singapore