[1] Northwestern Univ, Prevent Med, Chicago, IL 60611 USA
[2] Univ Minnesota, Dept Lab Med & Pathol, Minneapolis, MN 55455 USA
[3] Univ Minnesota, Sch Publ Hlth, Minneapolis, MN USA
[4] Univ Texas Hlth Sci Cntr Houston, McGovern Med Sch, Houston, TX USA
[5] Northwestern Univ, Prevent Med, Birmingham, AL USA
[6] Kaiser Permanente, Div Rsch, Oakland, CA USA
[7] Univ Alabama Birmingham, Dept Med, Birmingham, AL 35294 USA