1. VA Connecticut Healthcare System , West Haven, Connecticut, USA
2. Department of Medicine, Yale University , New Haven, Connecticut, USA
3. Department of Medicine, Vanderbilt University School of Medicine , Nashville, Tennessee, USA
4. Veterans Health Administration-Tennessee Valley Healthcare System Geriatric Research, Education and Clinical Center (GRECC) , Nashville, Tennessee, USA
5. VA Greater Los Angeles Healthcare System , Los Angeles, California, USA
6. David Geffen School of Medicine at UCLA , Los Angeles, California, USA
7. Infectious Diseases Section, Department of Medicine, Michael E. DeBakey VAMC, Baylor College of Medicine , Houston, Texas, USA
8. James J. Peterson VAMC , Bronx, New York, USA
9. Department of Medicine, Harborview Medical Center, University of Washington , Seattle, Washington, USA