[1] Univ Texas Med Branch, Div Pulm Crit Care & Sleep Med, Dept Internal Med, Galveston, TX 77555 USA
[2] Univ Texas MD Anderson Canc Ctr, Dept Hlth Serv Res, Houston, TX 77030 USA
[3] Univ Texas MD Anderson Canc Ctr, Div Canc Prevent & Populat Sci, Dept Symptom Res, Houston, TX 77030 USA
[4] Massachusetts Gen Hosp, Harvard Med Sch, Div Gen Internal Med, Boston, MA 02114 USA