[1] Natl Univ Singapore, Duke NUS Med Sch, Singapore, Singapore
[2] Singapore Hlth Serv, Hlth Serv Res Ctr, Singapore, Singapore
[3] Monash Univ, Fac Med Nursing & Hlth Sci, Melbourne, Vic, Australia
[4] Singapore Gen Hosp, Dept Emergency Med, Singapore, Singapore
[5] Duke Univ, Sch Med, Dept Med, Durham, NC 27706 USA
[6] Singapore Gen Hosp, Dept Anaesthesiol, Singapore, Singapore
[7] Singapore Gen Hosp, Dept Resp & Crit Care Med, Singapore, Singapore
[8] Singapore Natl Eye Ctr, Singapore, Singapore
[9] Singapore Gen Hosp, Dept Infect Dis, Singapore, Singapore