1 From the Department of Medicine, Massachusetts General Hospital, Boston (D.K.); the New York City Health and Hospitals Corporation (D.A.C.), the Department of Population Health, New York University Langone Medical Center (D.A.C.), and the Department of Economics, Hunter College and the Graduate Center, City University of New York (K.B.) - all in New York; Venrock Partners, Palo Alto, CA (R.K.); the Robert Wood Johnson Foundation Clinical Scholars Program, University of Pennsylvania, Philadelphia (A.R.); and the Centers for Medicare and Medicaid Services, Baltimore (P.H.C., R.R.).