[1] Framingham Heart Dis Epidemiol Study, Framingham, MA 01702 USA
[2] Boston Univ, Sch Publ Hlth, Dept Biostat, Boston, MA USA
[3] Mayo Clin, Rochester, MN USA
[4] Vet Adm Hosp, W Roxbury, MA USA
[5] Cardiovasc Engn Inc, Norwood, MA USA
[6] Boston Univ, Sch Med, Prevent Med Sect, Boston, MA 02118 USA
[7] Boston Univ, Sch Med, Cardiol Sect, Boston, MA 02118 USA