[1] Duke Univ, Dept Family Med & Community Hlth, 2200 West Main St,Room 461, Durham, NC 27705 USA
[2] Duke Univ, Dept Populat Hlth Sci, Durham, NC USA
[3] Duke Univ, Duke Clin Res Inst, Durham, NC USA
[4] Copenhagen Univ Hosp Gentofte, Dept Cardiol, Hellerup, Denmark
[5] Univ Colorado, Dept Emergency Med, Denver, CO USA
[6] Duke Natl Univ Singapore Med Sch, Hlth Serv & Syst Res, Singapore, Singapore
[7] Singapore Gen Hosp, Dept Emergency Med, Singapore, Singapore
[8] Emory Univ, Rollins Sch Publ Hlth, Atlanta, GA USA
[9] Emory Univ, Dept Emergency Med, Sch Med, Atlanta, GA USA