[1] Johns Hopkins Univ, Dept Surg, 2000 E Monument St, Baltimore, MD 21205 USA
[2] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Epidemiol, Baltimore, MD USA
[3] Denver Hlth Med Ctr, Dept Emergency Med, Denver, CO USA
[4] Univ Colorado, Sch Med, Dept Emergency Med, Aurora, CO USA
[5] Colorado Sch Publ Hlth, Dept Epidemiol, Aurora, CO USA
[6] Ohio State Univ, Dept Surg, Wexner Med Ctr, Columbus, OH 43210 USA