[1] Kaiser Permanente Colorado, Inst Hlth Res, Denver, CO USA
[2] Univ Colorado, Denver, CO 80202 USA
[3] Duke Univ, Med Ctr, Duke Clin Res Inst, Durham, NC USA
[4] Stanford Sch Med, Palo Alto, CA USA
[5] St Lukes Hosp, Mid Amer Heart Inst, Kansas City, MO 64111 USA
[6] Univ Missouri, Sch Med, Kansas City, MO 64108 USA
[7] Denver VA Med Ctr, Denver, CO USA
[8] Tennesse Vallry Hlth Syst VA, Nashville, TN USA
[9] Vanderbilt Univ, Med Ctr, Nashville, TN USA