1. Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia (A.S.N., S.A.K., J.G.).
2. Leonard Davis Institute of Health Economics (A.S.N., S.A.K., E.D., P.C., N.D.D., P.W.G., J.G.), University of Pennsylvania, Philadelphia, PA.
3. Penn Cardiovascular Outcomes, Quality, and Evaluative Research Center, Cardiovascular Institute (A.S.N., S.A.K., E.D., N.D.D., P.W.G., J.G.), University of Pennsylvania, Philadelphia, PA.
4. Baylor College of Medicine, Houston, TX (R.M.S.).
5. Division of General Internal Medicine, Perelman School of Medicine (P.C., P.W.G.), University of Pennsylvania, Philadelphia, PA.
6. Division of Cardiovascular Surgery (N.D.D.), University of Pennsylvania, Philadelphia, PA.
7. Division of Cardiology, University of Colorado School of Medicine, Aurora (S.W.W.).
8. Richard and Susan Smith Center for Outcomes Research in Cardiology, Beth Israel Deaconess Medical Center, Boston, MA (R.W.Y.).
9. Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA (P.W.G., J.G.).