1. VA Cooperative Studies Program Epidemiology Center–Durham, Durham VA Health Care System, Durham, North Carolina
2. Center for Clinical Research Network Coordination, Division of Biostatistics and Epidemiology, RTI International, Durham, North Carolina
3. Duke Molecular Physiology Institute, School of Medicine, Duke University, Durham, North Carolina
4. Department of Biostatistics and Bioinformatics, School of Medicine, Duke University, Durham, North Carolina
5. Durham Center for Health Services Research in Primary Care, Durham VA Health Care System, Durham, North Carolina
6. Division of General Internal Medicine, School of Medicine, Duke University, Durham, North Carolina
7. William S. Middleton Memorial Veterans Hospital, Department of Veterans Affairs, Madison, Wisconsin
8. Department of Surgery, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
9. Miami VA Healthcare System, Miami, Florida
10. Institute for Neuro-Immune Medicine, Dr. Kiran C. Patel College of Osteopathic Medicine, Nova Southeastern University, Fort Lauderdale, Florida
11. Massachusetts Veterans Epidemiology Research and Information Center, VA Boston Healthcare System, Boston, Massachusetts
12. Post-Deployment Health Epidemiology Program, Office of Patient Care Services, Department of Veterans Affairs, Washington, DC
13. War Related Illness and Injury Study Center, VA New Jersey Health Care System, East Orange, New Jersey
14. Department of Medicine, Rutgers New Jersey Medical School, Newark, New Jersey
15. Division of Gastroenterology, Duke University Medical Center, Durham, North Carolina