[1] VA Boston Healthcare Syst, MD Surg Serv 112, Dept Surg, W Roxbury, MA 02132 USA
[2] Harvard Univ, Sch Med, Boston, MA 02115 USA
[3] Brigham & Womens Hosp, Boston, MA 02115 USA
[4] Univ Colorado Hlth Outcomes Program, Aurora, CO USA
[5] Massachusetts Gen Hosp & Partners Healthcare Syst, Inst Hlth Policy, Boston, MA USA
[6] Univ Illinois Hosp, Dept Surg, Chicago, IL USA
[7] Univ Illinois, Coll Med, Chicago, IL USA
[8] Amer Coll Surg, Chicago, IL USA
[9] Univ Virginia, Sch Med, Charlottesville, VA 22908 USA
[10] Univ Michigan, Ann Arbor, MI 48109 USA
[11] Atlanta VA Med Ctr, Dept Surg, Decatur, GA USA
[12] Emory Univ, Atlanta, GA 30322 USA
[13] Wayne State Univ, Sch Med, Detroit, MI USA
[14] George E Whalen Salt Lake City VA Hlth Care Syste, Salt Lake City, UT USA
[15] Univ Utah, Salt Lake City, UT USA
[16] Univ Colorado, Hlth Sci Ctr, Denver, CO 80202 USA
[17] Dept Vet Affairs, Natl Surg Qual Improvement Program, Off Patient Care Serv, Aurora, CO USA