1. From the Institute for Clinical Research and Health Policy Studies, Tufts Medical Center (L.K.L., S.K.P., T.A.T., J.T.C.), and Departments of Medicine (L.K.L, S.K.P., T.A.T., J.T.C.) and Pediatrics (L.K.L., S.K.P.), Tufts University School of Medicine, Boston, Mass; Department of Cardiology (M.E.A., J.W.N.), Children’s Hospital Boston, Boston, Mass; and Department of Pediatrics (M.E.A., J.W.N.), Harvard Medical School, Boston, Mass.