[1] Univ S Carolina, Dept Epidemiol & Biostat, Columbia, SC 29208 USA
[2] Univ S Carolina, Arnold Sch Publ Hlth, S Carolina Rural Hlth Res Ctr, Columbia, SC 29208 USA
[3] Univ S Carolina, Sch Med, Dept Family & Prevent Med, Columbia, SC 29208 USA
[4] Univ S Carolina, Dept Hlth Serv Management & Policy, Columbia, SC 29208 USA