[1] Johns Hopkins Univ, Welch Ctr Prevent Epidemiol & Clin Res, Baltimore, MD 21205 USA
[2] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Epidemiol, Baltimore, MD USA
[3] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Biostat, Baltimore, MD USA
[4] Johns Hopkins Univ, Sch Med, Dept Med, Baltimore, MD 21205 USA
[5] Univ Minnesota, Sch Publ Hlth, Div Epidemiol, Minneapolis, MN USA
[6] Univ Mississippi, Med Ctr, Dept Med, Jackson, MS 39216 USA