[1] Duke Univ, Med Ctr, Dept Surg, Durham, NC 27710 USA
[2] Duke Univ, Med Ctr, Dept Biostat & Bioinformat, Durham, NC 27710 USA
[3] Duke Univ, Med Ctr, Dept Med, Div Cardiol, Durham, NC 27710 USA
[4] Duke Univ, Med Ctr, Outcomes Res & Assessment Grp, Durham, NC 27710 USA
[5] Univ Basel Hosp, Dept Surg, Div Gen Surg, CH-4031 Basel, Switzerland
[6] Univ Alabama Birmingham, Sch Med, Dept Surg,Birmingham Atlanta VA,GRECC, Birmingham VA Med Ctr,Alabama Qual Assurance Fdn, Birmingham, AL 35294 USA
[7] Univ Alabama Birmingham, Ctr Aging, Birmingham, AL USA