[1] Univ Vermont, Coll Med, Dept Pathol, Burlington, VT 05405 USA
[2] Univ Vermont, Coll Med, Dept Biochem, Burlington, VT 05405 USA
[3] Univ Vermont, Coll Med, Lab Clin Biochem Res, Burlington, VT 05405 USA
[4] Univ Washington, Dept Biostat, Seattle, WA 98195 USA
[5] Wake Forest Univ, Bowman Gray Sch Med, Dept Internal Med, Winston Salem, NC 27103 USA
[6] Wake Forest Univ, Bowman Gray Sch Med, Dept Publ Hlth Sci, Winston Salem, NC 27103 USA
[7] Johns Hopkins Univ, Dept Med, Baltimore, MD USA
[8] Johns Hopkins Univ, Dept Epidemiol, Baltimore, MD USA
[9] London Sch Hyg & Trop Med, Dept Epidemiol & Populat Sci, London WC1, England
[10] NHLBI, Div Epidemiol & Clin Applicat, NIH, Bethesda, MD 20892 USA