1. Division of Cardiac Surgery, Department of Surgery, Veterans Affairs Boston Healthcare System, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
2. Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
3. Cooperative Studies Program, Perry Point/Baltimore Coordinating Center, Office of Research and Development, US Department of Veterans Affairs, Perry Point, Maryland
4. VA Eastern Colorado Healthcare System, Denver
5. VA Health Economics Resource Center, Department of Surgery, Stanford University, Palo Alto, California
6. Cleveland Clinic, Cleveland, Ohio
7. Perry Point Cooperative Studies Program Coordinating Center, Office of Research and Development, US Department of Veterans Affairs, Perry Point, Maryland
8. Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore