[1] Univ Alabama Birmingham, Birmingham VA Med Ctr, Deep S Cent Effectiveness Res, Birmingham, AL USA
[2] Univ Alabama Birmingham, Dept Surg, Birmingham, AL USA
[3] Boston Univ, Dept Surg, Boston, MA 02215 USA
[4] VA Boston Hlth Care Syst, Dept Surg, W Roxbury, MA USA
[5] VA Cooperat Studies Program Coordinating Ctr, Hines, IL USA
[6] Northwestern Univ, Feinberg Sch Med, Dept Preventat Med, Chicago, IL 60611 USA
[7] Univ Illinois, Coll Med, Dept Surg, Chicago, IL 60680 USA
[8] Univ Utah, VA Med Ctr, Salt Lake City, UT 84112 USA
[9] Univ Utah, Dept Surg, Salt Lake City, UT 84112 USA