1. John W. Deming Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana, USA.
2. School of Public Health, Biostatistics Program, LSUHSC, New Orleans, Louisiana, USA.
3. School of Public Health, Behavioral and Community Health Sciences Program, LSUHSC, New Orleans, Louisiana, USA.
4. Lousisana State University Health Care Services Division, New Orleans, Louisiana, USA.
5. Section of Pulmonary Diseases, Critical Care, and Environmental Medicine, Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana, USA.