1. From the Division of Health and Environment, Abt Associates, Rockville, MD (M.J.T., B.F., S.B.); the Department of Health Care Policy, Harvard Medical School, and the Division of General Internal Medicine and Primary Care, Brigham and Women’s Hospital, Boston (J.M.M.); the Center for Medicare and Medicaid Innovation, Baltimore (D.J.N.); and L&M Policy Research, Washington, DC (B.M.).