[1] Natl Univ Hlth Syst, Prevent Med Residency Programme, Singapore, Singapore
[2] Natl Univ Singapore Hosp, Div Resp & Crit Care Med, Singapore 117548, Singapore
[3] Natl Univ Singapore Hosp, Univ Med Cluster, Div Gen Med & Therapeut, Singapore 117548, Singapore
[4] Natl Univ Singapore Hosp, Univ Med Cluster, Div Neurol, Singapore 117548, Singapore