1. Division of Pulmonary, Allergy, and Critical Care, Department of Medicine, Duke University School of Medicine, Durham, North Carolina
2. Durham Veterans Affairs Medical Center, Durham, North Carolina
3. Duke Global Health Institute, Duke University, Durham, North Carolina
4. Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, North Carolina
5. Department of Population Health Sciences, Duke University, Durham, North Carolina