1. Division of General Internal Medicine and Public Health, Vanderbilt University Medical Center, Nashville, Tennessee, USA
2. GRECC, Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, Tennessee, USA
3. Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
4. Division of Epidemiology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
5. University of Tennessee, School of Medicine, Memphis, Tennessee, USA
6. Tulane University School of Medicine, New Orleans, Louisiana, USA