1 Richard A and Susan F Smith Center for Outcomes Research, Beth Israel Deaconess Medical Center, Boston, MA, USA; Department of Medicine, Brigham and Women's Hospital, Boston, MA 02215, USA. Electronic address: mliu8@mgb.org.
2 Department of Surgery, Brigham and Women's Hospital, Boston, MA, USA.
3 Richard A and Susan F Smith Center for Outcomes Research, Beth Israel Deaconess Medical Center, Boston, MA, USA.
4 Department of Medicine, Brigham and Women's Hospital, Boston, MA 02215, USA.
5 Richard A and Susan F Smith Center for Outcomes Research, Beth Israel Deaconess Medical Center, Boston, MA, USA; Department of Health Policy and Management, Harvard T H Chan School of Public Health, Boston, MA, USA.