1 Emergency Medicine Department, National University Hospital, National University Health System, Singapore. Electronic address: daniel_chor@nuhs.edu.sg.
2 Emergency Department, Ng Teng Fong General Hospital, National University Health System, Singapore.
3 Emergency Medicine Department, National University Hospital, National University Health System, Singapore.
4 Urgent Care Centre, Alexandra Hospital, National University Health System, Singapore.
5 Emergency Medicine Department, National University Hospital, National University Health System, Singapore; Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.