1. Department of Medicine, Boston Veterans Administration Healthcare System, Harvard Medical School, Boston, Massachusetts
2. Massachusetts General Hospital and Partners Healthcare System, Institute for Health Policy, 50 Staniford Street, Boston, Massachusetts 02114; e-mail: jdaley1
3. Veterans Administration Cooperative Studies Program Coordinating Center, Fifth and Roosevelt Roads, Hines, Illinois 60141;
4. Department of Surgery, Brigham and Women's Hospital Harvard Medical School, 1400 VFW Parkway, West Roxbury Massachusetts 02132;
5. Boston Veterans Administration Healthcare System, 1400 VFW Parkway, West Roxbury Massachusetts 02132;