1. Division of Population Health, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, GA, USA
2. Division of Pulmonary, Allergy, and Critical Care Medicine, Duke University School of Medicine, Durham, NC, USA
3. Section on Pulmonary, Critical Care, Allergy & Immunologic Disease, Wake Forest University School of Medicine, Winston Salem, NC, USA
4. Chronic Disease Epidemiology Office, South Carolina Department of Health and Environmental Control, Columbia, SC, USA
5. Division of Pulmonary, Critical Care, and Sleep Medicine, Pulmonary Epidemiology Research Laboratory, University of Kentucky, Lexington, KY, USA
6. Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, Medical University of South Carolina, Charleston, SC, USA