[1] Duke Univ, Med Ctr, Div Geriatr, Durham, NC 27710 USA
[2] Duke Univ, Dept Med, Durham, NC 27710 USA
[3] Duke Univ, Ctr Study Aging & Human Dev, Durham, NC 27710 USA
[4] Duke Univ, Ctr Palliat Care, Durham, NC 27710 USA
[5] Duke Univ, Dept Biostat & Bioinformat, Durham, NC 27710 USA