[1] Harvard Univ, Massachusetts Gen Hosp, Sch Med, Dept Emergency Med, Boston, MA USA
[2] Univ Laval, Inst Univ Cardiol & Pneumol, Hop Laval, Quebec City, PQ, Canada
[3] Natl Jewish Hlth, Dept Med, Denver, CO USA
[4] Univ Colorado, Dept Med, Denver, CO USA
[5] Univ Wisconsin, Sch Med, Dept Med, Madison, WI USA
[6] GlaxoSmithKline, Res Triangle Pk, NC USA