[1] Washington Univ, Dept Med, Div Gen Med Sci, Sch Med St Louis, St Louis, MO USA
[2] Washington Univ, Inst Informat, Sch Med St Louis, St Louis, MO 63110 USA
[3] Corporal Michael Crescenz VA Med Ctr, Ctr Hlth Equ Res & Promot CHERP, Philadelphia, PA USA
[4] Univ Penn, Dept Med, Div Gen Internal Med, Perelman Sch Med, Philadelphia, PA 19104 USA
[5] Univ Penn, Leonard Davis Inst Hlth Econ, Philadelphia, PA 19104 USA