[1] Duke NUS Med Sch, Lien Ctr Palliat Care, 8 Coll Rd, Singapore 169857, Singapore
[2] Duke NUS Med Sch, Hlth Serv & Syst Res, 8 Coll Rd, Singapore 169857, Singapore
[3] Natl Heart Ctr Singapore, 5 Hosp Dr, Singapore 169609, Singapore
[4] Duke Univ, Duke Global Hlth Inst, 310 Trent Dr, Durham, NC 27710 USA