[1] Wake Forest Univ, Sch Med, Div Publ Hlth Sci, Winston Salem, NC 27157 USA
[2] GlaxoSmithKline Inc, Res Triangle Pk, NC USA
[3] Univ Washington, Dept Biostat, Seattle, WA 98195 USA
[4] Univ Vermont, Coll Med, Dept Pathol, Burlington, VT 05405 USA
[5] Univ Vermont, Coll Med, Dept Med, Burlington, VT 05405 USA