1. Department of Internal Medicine, Allegheny Health Network, Pittsburgh, PA 15212, USA
2. Department of Mathematics and Statistics, University of New Mexico, Albuquerque, NM 87106, USA
3. Division of Pulmonology and Critical Care, Allegheny Health Network, Pittsburg, PA 15212, USA
4. Department of Internal Medicine, University of New Mexico, Albuquerque, NM 87106, USA
5. Department of Hospital Medicine, Mary Washington Hospital, Fredericksburg, VA 22401, USA
6. Department of Internal Medicine, University of Kansas Medical Center, Kansas City, KS 66160, USA