1. Department of Health Services Administration, University of Maryland School of Public Health, College Park, MD, USA
2. Department of Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
3. Leonard Davis Institute of Health Economics, University of Pennsylvania, Philadelphia, PA, USA
4. Hospital of the University of Pennsylvania, Pulmonary, Allergy, and Critical Care Division, Philadelphia, PA, USA
5. Department of Medicine, Division of General Internal Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
6. Department of Health Policy & Management, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA