1 Department of Health Policy and Management, Harvard T. H. Chan School of Public Health, Boston, Massachusetts.
2 Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
3 Department of Medicine, Harvard Medical School, Boston, Massachusetts.
4 Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology, Division of Cardiology, Beth Israel Deaconess Medical Center, Boston, Massachusetts.