[1] Harvard Univ, Sch Med, Brigham & Womens Hosp, Boston, MA 02115 USA
[2] Harvard Univ, Sch Med, Brigham & Womens Hosp, Ctr Surg & Publ Hlth, Boston, MA USA
[3] Harvard Univ, Sch Med, Sch Publ Hlth, Boston, MA USA
[4] Dept Vet Affairs, Natl Surg Qual Improvement Program, Denver, CO USA
[5] Univ Colorado Hlth Outcomes Program, Aurora, CO USA
[6] Univ Texas, SW Med Ctr, VA N Texas Hlth Care Syst, Dallas, TX USA
[7] Vet Affairs Boston Healthcare Syst, West Roxbury, MA USA