[1] Duke Univ, Sch Med, Dept Populat Hlth Sci, Durham, NC 27701 USA
[2] Duke Univ, Duke Clin Res Inst, Durham, NC 27701 USA
[3] Kaiser Permanence Northern Calif, Div Res, Oakland, CA USA
[4] Duke Univ, Sch Med, Dept Med, Durham, NC 27701 USA
[5] Duke Univ, Sch Med, Dept Community & Family Med, Durham, NC 27701 USA
[6] Univ Kansas, Med Ctr, Dept Populat Hlth, Kansas City, KS 66103 USA
[7] Univ Kansas, Med Ctr, Dept Anesthesiol, Kansas City, KS 66103 USA