1. Department of Surgery, Veterans Affairs Boston Healthcare System, West Roxbury, Massachusetts
2. Research Office, Veterans Affairs Health Economics and Research Center, Palo Alto, California
3. Department of Surgery, Stanford University, Palo Alto, California
4. Department of Medicine, Rocky Mountain Regional Veterans Affairs Medical Center, Aurora, Colorado
5. Division of Cardiology, Department of Medicine, University of Colorado School of Medicine, Aurora
6. Department of Emergency Medicine, Mayo Clinic, Rochester, Minnesota
7. Research Office, Veterans Affairs Cooperative Studies Program, Perry Point, Maryland
8. Department of Surgery, Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin
9. Division of Cardiothoracic Surgery, Department of Surgery, Medical College of Wisconsin, Milwaukee
10. Division of Cardiothoracic Surgery, Department of Surgery, University of Colorado School of Medicine, Aurora
11. Department of Surgery, Rocky Mountain Regional Veterans Affairs Medical Center, Aurora, Colorado
12. Research and Development Office, Northport Veterans Affairs Medical Center, Northport, New York
13. Department of Surgery, Stony Brook University Renaissance School of Medicine, Stony Brook, New York