[1] Harvard Univ, Sch Med, Dept Hlth Care Policy, Boston, MA 02115 USA
[2] Brigham & Womens Hosp, Dept Med, Div Gen Internal Med, 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
[5] Univ Alabama Birmingham, Dept Med, Div Prevent Med, Birmingham, AL 35294 USA
[6] Univ Minnesota, Div Hlth Policy & Management, Minneapolis, MN USA
[7] Inst Clin Evaluat Sci, Toronto, ON, Canada
[8] Univ Toronto, Toronto, ON, Canada
[9] RAND Corp, Santa Monica, CA USA
[10] Univ Calif Los Angeles, Dept Med, Div Gen Internal Med, Los Angeles, CA 90024 USA