[1] Massachusetts Gen Hosp, Dept Surg, Boston, MA 02114 USA
[2] Harvard Univ, Sch Publ Hlth, Dept Hlth Policy & Management, Boston, MA 02115 USA
[3] Brigham & Womens Hosp, Dept Surg, Boston, MA 02115 USA
[4] Brigham & Womens Hosp, Ctr Surg & Publ Hlth, Boston, MA 02115 USA