1. VA Health Care System, Durham, NC, USA
2. Duke University Medical Center, Durham, NC, USA
3. Duke University, Durham, NC, USA
4. Salem VA Medical Center, VA, USA
5. Virginia Tech Carilion School of Medicine, Roanoke, USA
6. VA Greater Los Angeles Healthcare System, CA, USA
7. David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
8. Miami Healthcare System, FL, USA
9. University of Miami, Miller School of Medicine, FL, USA
10. VA Maryland Health Care System, Baltimore, USA
11. University of Maryland School of Medicine, Baltimore, USA
12. VA Medical Center, Canandaigua, NY, USA
13. VA Pacific Health Care System, Honolulu, HI, USA
14. VA Boston Healthcare System, MA, USA
15. Harvard Medical School, Boston, MA, USA
16. VA Ann Arbor Healthcare System, MI, USA
17. University of Michigan, Ann Arbor, USA
18. Central Arkansas Veterans Healthcare System, Little Rock, USA
19. University of Arkansas for Medical Sciences, Little Rock, USA
20. Eastern Colorado Health Care System, Aurora, USA
21. Unverisity of Colorado, Aurora, USA
22. VA Pittsburgh Healthcare System, PA, USA
23. University of Pittsburgh, PA, USA
24. University of Pittsburgh Medical Center, PA, USA
25. VA Puget Sound Health Care System, Seattle, WA, USA
26. University of Washington, Seattle, USA
27. Cincinnati VA Medical Center, OH, USA