[1] Univ Calif Los Angeles, David Geffen Sch Med, Dept Med, Div Pulm & Crit Care Med, Los Angeles, CA 90095 USA
[2] Chulalongkorn Univ, Fac Med, King Chulalongkorn Mem Hosp, Div Pulm & Crit Care Med,Dept Med, Bangkok 10330, Thailand
[3] Univ Calif Los Angeles, David Geffen Sch Med, Dept Med, Div Gen Internal Med & Hlth Serv Res, Los Angeles, CA 90024 USA