1. Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology, Division of Cardiology, Beth Israel Deaconess Medical Center, and Harvard Medical School, Boston, Massachusetts (R.A., R.W.Y., N.C., R.K.W., D.S.K.)
2. Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California (K.B.)
3. Harvard Medical School, Boston, Massachusetts (Y.S.)
4. Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology, Division of Cardiology, Beth Israel Deaconess Medical Center, Boston, Massachusetts (C.S.).