[1] Univ Alabama Birmingham, Dept Med, Div Cardiovasc Dis, Birmingham, AL 35294 USA
[2] Univ Alabama Birmingham, Sch Publ Hlth, Dept Biostat, Birmingham, AL USA
[3] Univ Vermont, Larner Coll Med, Dept Med, Burlington, VT USA
[4] Med Univ South Carolina, Coll Med, Dept Neurol, Charleston, SC USA
[5] Univ Alabama Birmingham, Sch Publ Hlth, Dept Epidemiol, Birmingham, AL USA