1 Department of Medicine, National University Hospital, Singapore; Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
2 Department of General Surgery, National University Hospital, Singapore.
3 Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Division of Respiratory & Critical Care Medicine, Department of Medicine, National University Hospital, Singapore.
4 Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Fast and Chronic Programme, Alexandra Hospital, Singapore; Division of Advanced Internal Medicine, Department of Medicine, National University Hospital, Singapore. Electronic address: desmond_teo@nuhs.edu.sg.