[1] Univ Minnesota, Div Epidemiol, Minneapolis, MN 55454 USA
[2] Univ N Carolina, Dept Epidemiol, Chapel Hill, NC USA
[3] Univ N Carolina, Dept Biostat, Chapel Hill, NC USA
[4] Wake Forest Sch Med, Dept Publ Hlth Sci, Winston Salem, NC USA
[5] NHLBI, Epidemiol & Biometry Program, Bethesda, MD 20892 USA
[6] Washington Univ, Div Biostat, St Louis, MO USA
[7] Univ Utah, Dept Psychiat, Salt Lake City, UT USA
[8] Boston Univ, Sch Med, Prevent Med & Epidemiol Sect, Boston, MA 02118 USA