1. Department of Health Care Policy, Harvard Medical School, Massachusetts General Hospital, Boston, MA
2. National Bureau of Economic Research, Cambridge, MA
3. Department of Economics, Columbia University, New York, NY
4. Division of Cardiology, Harvard Medical School, Massachusetts General Hospital, Boston, MA
5. Smith Center for Outcomes Research in Cardiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
6. Leonard D. Schaeffer Center for Health Policy and Economics, University of Southern California, Los Angeles, CA