[1] Univ N Carolina, Div Gen Med & Clin Epidemiol, Dept Social Med, Sch Med, Chapel Hill, NC 27599 USA
[2] Univ N Carolina, Div Gen Med & Clin Epidemiol, Dept Internal Med, Sch Med, Chapel Hill, NC 27599 USA
[3] Yale Univ, Sch Med, Dept Internal Med, New Haven, CT 06520 USA
[4] Yale Univ, Sch Med, Dept Neurol, New Haven, CT 06520 USA
[5] Yale Univ, Sch Med, Dept Epidemiol & Publ Hlth, New Haven, CT 06520 USA
[6] Yale Univ, Sch Med, Dept Obstet & Gynecol, New Haven, CT 06510 USA