[1] Duke Clin Res Inst, Durham, NC USA
[2] Duke Univ, Med Ctr, Dept Med, Durham, NC 27710 USA
[3] Univ N Carolina, Sch Med, Dept Emergency Med, Chapel Hill, NC USA
[4] Wake Forest Univ, Bowman Gray Sch Med, Dept Emergency Med, Winston Salem, NC USA
[5] Carolinas Med Ctr, Dept Emergency Med, Charlotte, NC 28203 USA