[1] Northwestern Univ, Feinberg Sch Med, Dept Prevent Med, Chicago, IL 60611 USA
[2] Johns Hopkins Univ, Dept Med, Div Endocrinol, Baltimore, MD USA
[3] Univ Minnesota, Dept Epidemiol, Minneapolis, MN USA
[4] Stanford Univ, Sch Med, Stanford Ctr Res Dis Prevent, Palo Alto, CA 94304 USA
[5] Penn State Univ, Milton S Hershey Med Ctr, Dept Hlth Evaluat Sci, Hershey, PA 17033 USA